Retinopathy of prematurity screening by non-retinologists
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《印度儿科学杂志》
Abstract
Objective. To detect the screening efficiency of general ophthalmologists (ophthalmic residents) as well as non-ophthalmologists (pediatric residents and nurses posted in neonatal intensive care unit) in screening (ROP) retinopathy of prematurity on the basis of posterior pole vascular changes. Methods. Prospective consecutive review in a tertiary care hospital setting. Five groups (each comprising of one ophthalmic resident, one pediatric resident and a nurse) examined the posterior pole vessels of 200 eyes of ROP with a direct ophthalmoscope and compared with an ROP specialist using indirect ophthalmoscope. SPSS (Statistical Package for the Social Science), version 10.0 was used for the analysis. Results. Ophthalmic residents findings were: (sensitivity 95.68%, specificity 92.85%, positive predictive value 94.81%, negative predictive value 93.97%; pediatric residents findings were : (sensitivity 92.24%, specificity 88.09%, positive predictive value 91.45%, negative predictive value 89.15%); and nurses, finding were: (sensitivity 88.79%, specificity 85.71%, positive predictive value 89.56%, and negative predictive value 84.70%). The results had no statistically significant difference in diagnostic reliability. Kappa agreement analysis was significant for ophthalmic residents (0.887), pediatric residents (0.805) and nurses (0.744) compared with the ROP specialist. None of the children diagnosed with pre-threshold or threshold ROP was thought to have normal posterior pole vessels by the trainees. Conclusions. Given adequate training, general ophthalmologists and non-ophthalmologists (pediatricians and nurse practitioners) are independently reliable in detecting posterior pole changes in ROP babies using direct ophthalmoscope and can be provided with a screening protocol.
Keywords: Non-ophthalmologists; Retinopathy of prematurity; Screening; Training
How to cite this article:
Azad RV, Manjunatha NP, Pal N, Deorari AK. Retinopathy of prematurity screening by non-retinologists. Indian J Pediatr 2006;73:515-518
How to cite this URL:
Azad RV, Manjunatha NP, Pal N, Deorari AK. Retinopathy of prematurity screening by non-retinologists. Indian J Pediatr [serial online] 2006 [cited 2006 Jul 14];73:515-518. Available from: http://www.ijppediatricsindia.org/article.asp?issn=0019-5456;year=2006;volume=73;issue=6;spage=515;epage=518;aulast=Azad
Retinopathy of prematurity (ROP), a potentially blinding condition is a proliferative disorder of the developing retinal vasculature seen in the premature and low birth weight infants. The outcome ranges from minimal sequelae to bilateral, irreversible and total blindness in more advanced cases.[1] Incidence of this condition is rising rapidly in developing countries with improvements in neonatal care and increasing survival of very low birth infants.[2]
The blindness due to ROP is however preventable if the treatment is instituted at an appropriate time. The proven benefit of cryotherapy and laser photocoagulation has made it mandatory to ensure that all susceptible infants undergo screening examination, usually performed by an ROP specialist experienced in the diagnosis and management of infants with ROP.[3] The main aim of screening is to detect infants needing treatment for ROP. However, treatment itself is expensive, time consuming and stressful to the infant, which emphasizes the importance of adequate screening of infants with minimum of resources.[4]
Detailed examination of the peripheral retina may not be always possible, as ROP specialists are not consistently available at the community nurseries for follow-up examinations of infants who have been transferred to community nurseries prior to complete maturation of the retinal vessels. The frequency of ROP present in these infants and the lack of ROP specialists justify the risks and costs associated with the development of a screening technique for non-ophthalmologists when weighed against the failure to provide treatment to today's premature infants. The screening personnel should have the ability to detect the difference between normal blood vessels and engorged tortuous blood vessels (plus disease) exiting at the optic disc, suggesting the possibility of serious disease, elsewhere promoting a referral to a retinal specialist.[5]
The aim of the present study was to detect the efficacy of a training module in screening for ROP on the basis of posterior pole vascular changes for general ophthalmologists (ophthalmic residents) as well as non-ophthalmologists (pediatric residents and nurses posted in neonatal intensive care unit).
Material and Methods
he study group included 5 residents in ophthalmology (doing 3rd year postgraduatation), 5 residents in pediatrics (doing 3rd year postgraduation) and 5 nurses in neonatal intensive care units (doing 3rd year B Sc Nursing), all working in the same tertiary care hospital. All the participants went through 3 steps: Step I -Training period; Step II-Test period; Step III-Evaluation.
Step I: Training period
Duration of training period was of 3 weeks for all participants. Training modality included:
(i) A course of lectures: Firstly, the participants knowledge about ROP and direct ophthalmoscope was assessed. All participants were familiar with the term ROP except for 2 of the nurses. All the ophthalmology residents had good knowledge about ROP and the use of direct ophthalmoscope. All the pediatric residents had good knowledge of ROP, but only 3 were familiar with the use of direct ophthalmoscope. None of the nurses were familiar with the use of direct ophthalmoscope. A 2- hour-lecture about the basic concepts of ROP, including plus disease was delivered to cover the importance of ROP including etiopathogenesis, classification; and clinical photographs as well as slides of normal fundus and ROP fundus with plus disease were shown.
(ii) Fundus examination in adults by direct ophthalmoscope: Pediatric residents and nurses were taught to use direct ophthalmoscope in 12 and 16 patients each respectively. The participants performed fundus examination under full dilation of the pupil under the able supervision of ROP specialists (RVA, HK) to gain familiarity with the direct ophthalmoscope, its use in a clinically appropriate manner to detect abnormalities accurate ocular information.
(iii) Fundus examination in neonates by direct ophthalmoscope : ROP specialists demonstrated posterior pole vascular anatomy of premature neonates (normal as well as plus disease) using the teaching mirror of indirect ophthalmoscope. Then, the same findings were seen by the participants themselves using direct ophthalmoscope. The number of neonates examined was 8 by each resident in ophthalmology, 12 by each pediatric resident and 16 by each nurse.
Step II : Test period
This part of the study was conducted in the neonatal intensive care unit of our tertiary care hospital from July 2000 to July 2001. Neonates who had ROP with stage-1, 2, 3, pre-threshold and threshold disease were included in the study. Infants with ROP stage-4 or 5, inadequate pupillary dilation inhibiting direct ophthalmoscopy, opacity in the media obscuring the posterior pole view and prior knowledge of referral findings were excluded from the study. Pupillary dilation was obtained by sequential instillation of tropicamide 0.5% and phenylephrine 2.5% at 15 minutes interval starting 1 hour before examination.
The set of 15 trainees were subdivided into 5 groups of 3, each comprising an ophthalmic resident, a pediatric resident and a nurse. Each group of 3 persons screened the fundus of 40 eyes of ROP with a direct ophthalmoscope using a speculum and classified the posterior pole vessels as normal or abnormal. In addition to plus disease, a vessel pair was considered abnormal if there was venous dilation greater than twice the caliber of adjacent and normal-appearing posterior pole arterioles in the same eye, with or without accompanying dilation and tortuosity of retinal arterioles. These 200 eyes were evaluated independently by an ROP specialist using an indirect ophthalmoscope for posterior pole changes including plus disease, against whose findings those of the trainees were compared and evaluated. The ROP specialist was unaware of the findings of the trainees until each posterior pole examination completed and all data recorded.
Step III : Evaluation
The data was analyzed using SPSS (Statistical Package for Social Sciences) (Release 10.0.1,27.10.99, ?SPSS Inc.)
Results
Two hundred eyes of newborn infants were examined who satisfied the criterion. Of them, 119 eyes of male infants and 81 eyes of female infants were examined. Out of the 200 eyes, 84 eyes (42%) had ROP with normal posterior pole. Remaining 116 eyes had ROP with abnormal posterior pole vascular changes. Twenty one (10.5%) eyes had stage-3 ROP with plus disease, 22 eyes (11%) had stage 3 ROP with posterior pole vascular changes (excluding plus disease) and 73 eyes (36.5%) had ROP of stage-1 and 2 with posterior pole vascular changes.
Assessment of ophthalmic residents in detecting posterior pole vascular changes in ROP [Table - 1] showed that 111 out of 116 eyes with abnormal posterior pole vascular changes with ROP were correctly identified (True positives), the and rest of 5 eyes were incorrectly scored as normal (False negative). Seventy eight out of 84 eyes with normal posterior pole with ROP were correctly identified as normal (True negative) and 6 eyes were wrongly identified as abnormal (False positive). Ophthalmic residents had a sensitivity of 95.68%, specificity of 92.85%, positive predictive value 94.81% and negative predictive value 93.97%.
Assessment of pediatric residents in detecting posterior pole vascular changes in ROP [Table - 1] showed that 107 out of 116 eyes with abnormal posterior pole vascular changes with ROP were correctly identified (True positives) and the rest 9 eyes were wrongly identified as normal (False negative). Seventy four out of 84 eyes with normal posterior pole with ROP were correctly identified as normal (True negative) and 10 eyes were wrongly identified as abnormal (False positive). Pediatric residents had a sensitivity of 92.24%, specificity of 88.09%, positive predictive value 91.45% and negative predictive value 89.15%.
Assessment of nurses working in neonatal intensive care unit in detecting posterior pole vascular changes in ROP [Table - 1] showed that 103 out of 116 eyes with abnormal posterior pole vascular changes with ROP were correctly identified (True positives) and the rest 13 eyes were wrongly identified as normal (False negative). Seventy-two out of 84 eyes with normal posterior pole with ROP were correctly identified as normal (True negative) and 12 eyes were wrongly identified as abnormal (False positive). Nurses had a sensitivity of 88.79%, specificity of 85.71%, positive predictive value 89.56% and negative predictive value 84.70%.
None of the infants with pre-threshold or threshold ROP was thought to have normal posterior pole vessels by the ophthalmic residents, pediatric residents and nurses.
Comparison of the ability to detect abnormal posterior pole vascular changes by the participants with the ROP specialists were done using Kappa analysis, which showed strong significance with values being 0.887, 0.805 and 0.744 for ophthalmic residents, pediatric residents and nurses respectively. Comparison of the ability to detect venous dilation by the participants with the ROP specialists were done using Kappa analysis, which showed strong significance with values being 0.887, 0.785 and 0.724 for general ophthalmologists, pediatric residents and nurses respectively.
There was no statistically significant difference in diagnostic reliability for detection of posterior pole vascular changes using direct ophthalmoscope among the ophthalmic residents, pediatric residents and nurses. Similarly, there was no statistically significant difference in diagnostic reliability for detection of venous dilation by the participants.
Discussion
Increase in the incidence of blindness due to ROP has alerted us about the condition. In most of developing nations, ROP specialists are in inadequate number and most often they are not available at peripheral centers. The technique of screening by indirect ophthalmoscope requires high skill and a long learning curve. A number of studies were attempted in this regard to simplify and standardize the screening protocol, including a computer system for measuring dilation and tortuosity of the vessels.[6],[7] An even simplified method of screening the posterior pole vessels by health personnel could be of value, as it increases the likelihood that infants at risk for ROP will be appropriately examined and referred to the specialists.[8],[9],[10],[11]To devise such a method, a sign which indicates the severity of the disease and a simple instrument which needs less training and skill is necessary, without compromising outcome. In our study we have tried to appraise these aspects by evaluating the ability of health personnels including general ophthalmologists, pediatricians and nurses working in neonatal intensive care unit to detect posterior pole vascular changes including plus disease in ROP using a direct ophthalmoscope.
Plus disease in ROP has been used to describe eyes with sufficient vascular engorgement to cause marked dilation and tortuosity of both arterioles and venules in the posterior pole.[9] It is usually associated with abnormal ROP of stage-3 and above and rarely below stage-2.[9]
Direct ophthalmoscope is a much easier technique and requires less skill to learn when compared to indirect ophthalmoscope. Direct ophthalmoscope has proven to be the most valuable single test for diagnosing posterior pole findings as a tool for screening.[12],[13]
Saunders et al[9] suggested that non-ophthalmologists can detect posterior pole vascular abnormality in premature infants. The test sensitivities for non-ophthalmologist examiners (4th year medical students, pediatric residents and nurse practitioners) using direct and indirect ophthalmoscope were 96% and 92% respectively. A similar study conducted showed a significant correlation (p<0.001) between the non-ophthalmologist's (pediatrician) and the ophthalmologist's diagnosis of posterior pole vascular abnormalities. No infant with clinically important ROP (pre-threshold or worse) failed detection by this method.[11]
In this study both general ophthalmologists and non-ophthalmologists have been included as they are available at primary care centers. The duration of training period was well defined in this study. Duration of the training depended on the previous knowledge of the participants about the disease and the instrument. Predictive accuracy of the screening test was high and was statistically significant. Kappa analysis for comparing the ability to detect the posterior pole vascular change by the participants with the ROP specialist showed statistical significance. The ability of participants to detect the venous dilation was also analyzed. There was no statistical significance in diagnostic ability to detect venous dilation by all.
There was a high diagnostic sensitivity achieved at a substantial cost in terms of specificity in all the 3 study groups. Twenty eight out of 252 examinations were falsely detected as abnormal by the participants. Slight increase in over-diagnosis at primary screening level is acceptable as the less number of cases with the disease are missed and at the same time decrease the burden on the specialists.
This study has been the first of its kind to be carried out in a developing country (Indian subcontinent), where the ROP specialists are proportionately less in number. It provides relevant data indicating that general ophthalmologists as well as non-ophthalmologists (pediatricians and nurse practitioners) are independently reliable in detecting posterior pole changes in ROP babies, using direct ophthalmoscope, and therefore can be provided with a screening protocol which states the parameters for follow-up and referral of ROP cases. This shows that given adequate training, general as well as non-ophthalmologists can appropriately refer cases of ROP needing treatment to secondary or tertiary level hospitals so that appropriate management can be instituted for them by the ROP specialists.
References
1. Bremer, Fellows RR et al. Strabismus in premature infants in the first year of life. Arch Ophthalmol 1998; 116: 329-333.
2. Cryotherapy for retinopathy of prematurity cooperative group. Multicenter trial of cryotherapy for retinopathy of prematurity: snellen activity and structural outcome at five and a half years. Arch Ophthalmol 1996; 114: 417-424.
3. O'Keefe M, O'Reilly J, Lanigan B. Longer term visual outcome of eyes with retinopathy of prematurity treated with cryotherapy or diode laser. Br J Ophthalmol 1998; 82: 1246-1248.
4. Larsson E, Holmstrom G.Screening for retinopathy of prematurity: evaluation and modification of guidelines. Br J Ophthalmol 2002; 86 : 1399-1402.
5. Harrison RJ, Wild JM, Hobky. Referral patterns to an ophthalmic outpatient clinic by general practitioners and ophthalmic opticians and the role of these professionals in screening for ocular disease. BMJ 1957; 297 : 1102-1107.
6. Andruscavage L, Weissgold D J. Screening for retinopathy of prematurity. Br J Ophthalmol 2002; 86: 1127-1130.
7. Schwartz SD, Harrison SA, Ferrone PJ, Trese MT. Telemedical evaluation and management of retinopathy of prematurity using a fiberoptic digital fundus camera. Ophthalmology 2000; 107: 25-28.
8. Dhillon B, Wright E, Fleck BW. Screening for retinopathy of prematurity: are a lid speculum and scleral indentation necessary? J Pediatr Ophthalmol Strabismus 1993; 30 : 377-381.
9. Saunders RA, Bluestein EC, Sinatra RB, Wilson ME, O'Neil JW, Rust PF. The predictive value of posterior pole vessels in retinopathy of prematurity. J Pediatr Ophthalmol Strabismus 1995; 32 : 82-85.
10. Saunders RA, Margaret LD, Berland JE, Roberts EL, Powers BV, Rust PF. Non-ophthalmologist screening for retinopathy of prematurity. Br J Ophthalmol 2000; 84 : 130-134.
11. Saunders RA, Berland JE , Bluestein EC, , Donahue ML, Wilson ME, Rust PF.Can non-ophthalmologists screen for retinopathy of prematurity? J Pediatr Ophthalmol Strabismus 1995; 32: 302-304.
12. Harper R, Reeves B. The sensitivity and specificity of direct ophthalmoscopic optic disc assessment in screening for glaucoma: a multivariate analysis. Graefes Arch Clin Exp Ophthalmol 2000; 238 (12): 949-955.
13. Faigen M. The early detection of glaucoma in general practice. Aust Fam Physician 2000; 29(3): 282-285.(Azad Raj Vardhan, Manjuna)
Objective. To detect the screening efficiency of general ophthalmologists (ophthalmic residents) as well as non-ophthalmologists (pediatric residents and nurses posted in neonatal intensive care unit) in screening (ROP) retinopathy of prematurity on the basis of posterior pole vascular changes. Methods. Prospective consecutive review in a tertiary care hospital setting. Five groups (each comprising of one ophthalmic resident, one pediatric resident and a nurse) examined the posterior pole vessels of 200 eyes of ROP with a direct ophthalmoscope and compared with an ROP specialist using indirect ophthalmoscope. SPSS (Statistical Package for the Social Science), version 10.0 was used for the analysis. Results. Ophthalmic residents findings were: (sensitivity 95.68%, specificity 92.85%, positive predictive value 94.81%, negative predictive value 93.97%; pediatric residents findings were : (sensitivity 92.24%, specificity 88.09%, positive predictive value 91.45%, negative predictive value 89.15%); and nurses, finding were: (sensitivity 88.79%, specificity 85.71%, positive predictive value 89.56%, and negative predictive value 84.70%). The results had no statistically significant difference in diagnostic reliability. Kappa agreement analysis was significant for ophthalmic residents (0.887), pediatric residents (0.805) and nurses (0.744) compared with the ROP specialist. None of the children diagnosed with pre-threshold or threshold ROP was thought to have normal posterior pole vessels by the trainees. Conclusions. Given adequate training, general ophthalmologists and non-ophthalmologists (pediatricians and nurse practitioners) are independently reliable in detecting posterior pole changes in ROP babies using direct ophthalmoscope and can be provided with a screening protocol.
Keywords: Non-ophthalmologists; Retinopathy of prematurity; Screening; Training
How to cite this article:
Azad RV, Manjunatha NP, Pal N, Deorari AK. Retinopathy of prematurity screening by non-retinologists. Indian J Pediatr 2006;73:515-518
How to cite this URL:
Azad RV, Manjunatha NP, Pal N, Deorari AK. Retinopathy of prematurity screening by non-retinologists. Indian J Pediatr [serial online] 2006 [cited 2006 Jul 14];73:515-518. Available from: http://www.ijppediatricsindia.org/article.asp?issn=0019-5456;year=2006;volume=73;issue=6;spage=515;epage=518;aulast=Azad
Retinopathy of prematurity (ROP), a potentially blinding condition is a proliferative disorder of the developing retinal vasculature seen in the premature and low birth weight infants. The outcome ranges from minimal sequelae to bilateral, irreversible and total blindness in more advanced cases.[1] Incidence of this condition is rising rapidly in developing countries with improvements in neonatal care and increasing survival of very low birth infants.[2]
The blindness due to ROP is however preventable if the treatment is instituted at an appropriate time. The proven benefit of cryotherapy and laser photocoagulation has made it mandatory to ensure that all susceptible infants undergo screening examination, usually performed by an ROP specialist experienced in the diagnosis and management of infants with ROP.[3] The main aim of screening is to detect infants needing treatment for ROP. However, treatment itself is expensive, time consuming and stressful to the infant, which emphasizes the importance of adequate screening of infants with minimum of resources.[4]
Detailed examination of the peripheral retina may not be always possible, as ROP specialists are not consistently available at the community nurseries for follow-up examinations of infants who have been transferred to community nurseries prior to complete maturation of the retinal vessels. The frequency of ROP present in these infants and the lack of ROP specialists justify the risks and costs associated with the development of a screening technique for non-ophthalmologists when weighed against the failure to provide treatment to today's premature infants. The screening personnel should have the ability to detect the difference between normal blood vessels and engorged tortuous blood vessels (plus disease) exiting at the optic disc, suggesting the possibility of serious disease, elsewhere promoting a referral to a retinal specialist.[5]
The aim of the present study was to detect the efficacy of a training module in screening for ROP on the basis of posterior pole vascular changes for general ophthalmologists (ophthalmic residents) as well as non-ophthalmologists (pediatric residents and nurses posted in neonatal intensive care unit).
Material and Methods
he study group included 5 residents in ophthalmology (doing 3rd year postgraduatation), 5 residents in pediatrics (doing 3rd year postgraduation) and 5 nurses in neonatal intensive care units (doing 3rd year B Sc Nursing), all working in the same tertiary care hospital. All the participants went through 3 steps: Step I -Training period; Step II-Test period; Step III-Evaluation.
Step I: Training period
Duration of training period was of 3 weeks for all participants. Training modality included:
(i) A course of lectures: Firstly, the participants knowledge about ROP and direct ophthalmoscope was assessed. All participants were familiar with the term ROP except for 2 of the nurses. All the ophthalmology residents had good knowledge about ROP and the use of direct ophthalmoscope. All the pediatric residents had good knowledge of ROP, but only 3 were familiar with the use of direct ophthalmoscope. None of the nurses were familiar with the use of direct ophthalmoscope. A 2- hour-lecture about the basic concepts of ROP, including plus disease was delivered to cover the importance of ROP including etiopathogenesis, classification; and clinical photographs as well as slides of normal fundus and ROP fundus with plus disease were shown.
(ii) Fundus examination in adults by direct ophthalmoscope: Pediatric residents and nurses were taught to use direct ophthalmoscope in 12 and 16 patients each respectively. The participants performed fundus examination under full dilation of the pupil under the able supervision of ROP specialists (RVA, HK) to gain familiarity with the direct ophthalmoscope, its use in a clinically appropriate manner to detect abnormalities accurate ocular information.
(iii) Fundus examination in neonates by direct ophthalmoscope : ROP specialists demonstrated posterior pole vascular anatomy of premature neonates (normal as well as plus disease) using the teaching mirror of indirect ophthalmoscope. Then, the same findings were seen by the participants themselves using direct ophthalmoscope. The number of neonates examined was 8 by each resident in ophthalmology, 12 by each pediatric resident and 16 by each nurse.
Step II : Test period
This part of the study was conducted in the neonatal intensive care unit of our tertiary care hospital from July 2000 to July 2001. Neonates who had ROP with stage-1, 2, 3, pre-threshold and threshold disease were included in the study. Infants with ROP stage-4 or 5, inadequate pupillary dilation inhibiting direct ophthalmoscopy, opacity in the media obscuring the posterior pole view and prior knowledge of referral findings were excluded from the study. Pupillary dilation was obtained by sequential instillation of tropicamide 0.5% and phenylephrine 2.5% at 15 minutes interval starting 1 hour before examination.
The set of 15 trainees were subdivided into 5 groups of 3, each comprising an ophthalmic resident, a pediatric resident and a nurse. Each group of 3 persons screened the fundus of 40 eyes of ROP with a direct ophthalmoscope using a speculum and classified the posterior pole vessels as normal or abnormal. In addition to plus disease, a vessel pair was considered abnormal if there was venous dilation greater than twice the caliber of adjacent and normal-appearing posterior pole arterioles in the same eye, with or without accompanying dilation and tortuosity of retinal arterioles. These 200 eyes were evaluated independently by an ROP specialist using an indirect ophthalmoscope for posterior pole changes including plus disease, against whose findings those of the trainees were compared and evaluated. The ROP specialist was unaware of the findings of the trainees until each posterior pole examination completed and all data recorded.
Step III : Evaluation
The data was analyzed using SPSS (Statistical Package for Social Sciences) (Release 10.0.1,27.10.99, ?SPSS Inc.)
Results
Two hundred eyes of newborn infants were examined who satisfied the criterion. Of them, 119 eyes of male infants and 81 eyes of female infants were examined. Out of the 200 eyes, 84 eyes (42%) had ROP with normal posterior pole. Remaining 116 eyes had ROP with abnormal posterior pole vascular changes. Twenty one (10.5%) eyes had stage-3 ROP with plus disease, 22 eyes (11%) had stage 3 ROP with posterior pole vascular changes (excluding plus disease) and 73 eyes (36.5%) had ROP of stage-1 and 2 with posterior pole vascular changes.
Assessment of ophthalmic residents in detecting posterior pole vascular changes in ROP [Table - 1] showed that 111 out of 116 eyes with abnormal posterior pole vascular changes with ROP were correctly identified (True positives), the and rest of 5 eyes were incorrectly scored as normal (False negative). Seventy eight out of 84 eyes with normal posterior pole with ROP were correctly identified as normal (True negative) and 6 eyes were wrongly identified as abnormal (False positive). Ophthalmic residents had a sensitivity of 95.68%, specificity of 92.85%, positive predictive value 94.81% and negative predictive value 93.97%.
Assessment of pediatric residents in detecting posterior pole vascular changes in ROP [Table - 1] showed that 107 out of 116 eyes with abnormal posterior pole vascular changes with ROP were correctly identified (True positives) and the rest 9 eyes were wrongly identified as normal (False negative). Seventy four out of 84 eyes with normal posterior pole with ROP were correctly identified as normal (True negative) and 10 eyes were wrongly identified as abnormal (False positive). Pediatric residents had a sensitivity of 92.24%, specificity of 88.09%, positive predictive value 91.45% and negative predictive value 89.15%.
Assessment of nurses working in neonatal intensive care unit in detecting posterior pole vascular changes in ROP [Table - 1] showed that 103 out of 116 eyes with abnormal posterior pole vascular changes with ROP were correctly identified (True positives) and the rest 13 eyes were wrongly identified as normal (False negative). Seventy-two out of 84 eyes with normal posterior pole with ROP were correctly identified as normal (True negative) and 12 eyes were wrongly identified as abnormal (False positive). Nurses had a sensitivity of 88.79%, specificity of 85.71%, positive predictive value 89.56% and negative predictive value 84.70%.
None of the infants with pre-threshold or threshold ROP was thought to have normal posterior pole vessels by the ophthalmic residents, pediatric residents and nurses.
Comparison of the ability to detect abnormal posterior pole vascular changes by the participants with the ROP specialists were done using Kappa analysis, which showed strong significance with values being 0.887, 0.805 and 0.744 for ophthalmic residents, pediatric residents and nurses respectively. Comparison of the ability to detect venous dilation by the participants with the ROP specialists were done using Kappa analysis, which showed strong significance with values being 0.887, 0.785 and 0.724 for general ophthalmologists, pediatric residents and nurses respectively.
There was no statistically significant difference in diagnostic reliability for detection of posterior pole vascular changes using direct ophthalmoscope among the ophthalmic residents, pediatric residents and nurses. Similarly, there was no statistically significant difference in diagnostic reliability for detection of venous dilation by the participants.
Discussion
Increase in the incidence of blindness due to ROP has alerted us about the condition. In most of developing nations, ROP specialists are in inadequate number and most often they are not available at peripheral centers. The technique of screening by indirect ophthalmoscope requires high skill and a long learning curve. A number of studies were attempted in this regard to simplify and standardize the screening protocol, including a computer system for measuring dilation and tortuosity of the vessels.[6],[7] An even simplified method of screening the posterior pole vessels by health personnel could be of value, as it increases the likelihood that infants at risk for ROP will be appropriately examined and referred to the specialists.[8],[9],[10],[11]To devise such a method, a sign which indicates the severity of the disease and a simple instrument which needs less training and skill is necessary, without compromising outcome. In our study we have tried to appraise these aspects by evaluating the ability of health personnels including general ophthalmologists, pediatricians and nurses working in neonatal intensive care unit to detect posterior pole vascular changes including plus disease in ROP using a direct ophthalmoscope.
Plus disease in ROP has been used to describe eyes with sufficient vascular engorgement to cause marked dilation and tortuosity of both arterioles and venules in the posterior pole.[9] It is usually associated with abnormal ROP of stage-3 and above and rarely below stage-2.[9]
Direct ophthalmoscope is a much easier technique and requires less skill to learn when compared to indirect ophthalmoscope. Direct ophthalmoscope has proven to be the most valuable single test for diagnosing posterior pole findings as a tool for screening.[12],[13]
Saunders et al[9] suggested that non-ophthalmologists can detect posterior pole vascular abnormality in premature infants. The test sensitivities for non-ophthalmologist examiners (4th year medical students, pediatric residents and nurse practitioners) using direct and indirect ophthalmoscope were 96% and 92% respectively. A similar study conducted showed a significant correlation (p<0.001) between the non-ophthalmologist's (pediatrician) and the ophthalmologist's diagnosis of posterior pole vascular abnormalities. No infant with clinically important ROP (pre-threshold or worse) failed detection by this method.[11]
In this study both general ophthalmologists and non-ophthalmologists have been included as they are available at primary care centers. The duration of training period was well defined in this study. Duration of the training depended on the previous knowledge of the participants about the disease and the instrument. Predictive accuracy of the screening test was high and was statistically significant. Kappa analysis for comparing the ability to detect the posterior pole vascular change by the participants with the ROP specialist showed statistical significance. The ability of participants to detect the venous dilation was also analyzed. There was no statistical significance in diagnostic ability to detect venous dilation by all.
There was a high diagnostic sensitivity achieved at a substantial cost in terms of specificity in all the 3 study groups. Twenty eight out of 252 examinations were falsely detected as abnormal by the participants. Slight increase in over-diagnosis at primary screening level is acceptable as the less number of cases with the disease are missed and at the same time decrease the burden on the specialists.
This study has been the first of its kind to be carried out in a developing country (Indian subcontinent), where the ROP specialists are proportionately less in number. It provides relevant data indicating that general ophthalmologists as well as non-ophthalmologists (pediatricians and nurse practitioners) are independently reliable in detecting posterior pole changes in ROP babies, using direct ophthalmoscope, and therefore can be provided with a screening protocol which states the parameters for follow-up and referral of ROP cases. This shows that given adequate training, general as well as non-ophthalmologists can appropriately refer cases of ROP needing treatment to secondary or tertiary level hospitals so that appropriate management can be instituted for them by the ROP specialists.
References
1. Bremer, Fellows RR et al. Strabismus in premature infants in the first year of life. Arch Ophthalmol 1998; 116: 329-333.
2. Cryotherapy for retinopathy of prematurity cooperative group. Multicenter trial of cryotherapy for retinopathy of prematurity: snellen activity and structural outcome at five and a half years. Arch Ophthalmol 1996; 114: 417-424.
3. O'Keefe M, O'Reilly J, Lanigan B. Longer term visual outcome of eyes with retinopathy of prematurity treated with cryotherapy or diode laser. Br J Ophthalmol 1998; 82: 1246-1248.
4. Larsson E, Holmstrom G.Screening for retinopathy of prematurity: evaluation and modification of guidelines. Br J Ophthalmol 2002; 86 : 1399-1402.
5. Harrison RJ, Wild JM, Hobky. Referral patterns to an ophthalmic outpatient clinic by general practitioners and ophthalmic opticians and the role of these professionals in screening for ocular disease. BMJ 1957; 297 : 1102-1107.
6. Andruscavage L, Weissgold D J. Screening for retinopathy of prematurity. Br J Ophthalmol 2002; 86: 1127-1130.
7. Schwartz SD, Harrison SA, Ferrone PJ, Trese MT. Telemedical evaluation and management of retinopathy of prematurity using a fiberoptic digital fundus camera. Ophthalmology 2000; 107: 25-28.
8. Dhillon B, Wright E, Fleck BW. Screening for retinopathy of prematurity: are a lid speculum and scleral indentation necessary? J Pediatr Ophthalmol Strabismus 1993; 30 : 377-381.
9. Saunders RA, Bluestein EC, Sinatra RB, Wilson ME, O'Neil JW, Rust PF. The predictive value of posterior pole vessels in retinopathy of prematurity. J Pediatr Ophthalmol Strabismus 1995; 32 : 82-85.
10. Saunders RA, Margaret LD, Berland JE, Roberts EL, Powers BV, Rust PF. Non-ophthalmologist screening for retinopathy of prematurity. Br J Ophthalmol 2000; 84 : 130-134.
11. Saunders RA, Berland JE , Bluestein EC, , Donahue ML, Wilson ME, Rust PF.Can non-ophthalmologists screen for retinopathy of prematurity? J Pediatr Ophthalmol Strabismus 1995; 32: 302-304.
12. Harper R, Reeves B. The sensitivity and specificity of direct ophthalmoscopic optic disc assessment in screening for glaucoma: a multivariate analysis. Graefes Arch Clin Exp Ophthalmol 2000; 238 (12): 949-955.
13. Faigen M. The early detection of glaucoma in general practice. Aust Fam Physician 2000; 29(3): 282-285.(Azad Raj Vardhan, Manjuna)