Assessment of endothelium from donor corneas
Keywords: endothelium; pseudophakic donor corneas; aphakic donor corneas; organ culture/, http://www.100md.com
We read with interest an article by Meier et al.1 No doubt, this is an exciting issue on donor tissue harvesting and is more meaningful for the developing countries, where there is paucity of the donor material and, as a corollary to this, more people with corneal blindness. Further, because of more awareness towards cataract surgery as a result of the Vision 2020 programme, more patients are getting operated for cataract with a posterior chamber intraocular lens insertion (PCIOL). This is more relevant because of the increase in lifespan, as a result of improved health care, worldwide./, http://www.100md.com
However, we would like to comment on few additional aspects which would make the subject more clear. It is known that small incision cataract surgery influences less endothelial dysfunction than conventional extracapsular cataract extraction with PCIOL insertion.2 Similarly, endothelial cell loss following cataract surgery is a gradual process and continues for 1–2 years.3 Therefore, it would have been better to understand, and analyse, the type of cataract surgery and the duration between cataract surgery and actual cornea retrieval. Though the better endothelial health in eyes with phacoemulsification was considered to be because of the shorter time taken with the procedure we feel, besides the time factor, the use of a high viscosity viscoelastic agent which is frequently used during phacoemulsification is responsible as it provides more endothelial protection and less chance of intraoperative corneoendothelial touch.4
The authors have further highlighted that prestorage endothelial evaluation was not done as it was extremely difficult in unstained corneas. But it might have been possible with 0.25% trypan blue staining, rather than alizarine red S, as this technique neither precludes clinical use nor its evaluation by other staining procedures.57k]](t0, 百拇医药
Finally, the authors have rightly emphasised three essential factors of endothelial evaluation: (i) endothelial cell density, (ii) percentage of hexagonality, (iii) coefficient of variation. Often, it is observed that endothelial status is commented only regarding cell count. This is more so for the developing countries where the endothelial specular microscope is not provided with the software by which the hexagonality and coefficient of variation can be calculated. Thus many good studies lose their authenticity owing to lack of this essential provision.6 We are grateful to the authors for throwing light on this aspect. On the basis of authors’ comments and our own experience we suggest that while placing an order for specular microscope, it is mandatory to include this important software.
The authors are also commended by suggesting another source of donor tissue for penetrating keratoplasty.z'$(e0}, 百拇医药
Referencesz'$(e0}, 百拇医药
Meier FM, Tschanz SA, Ganzfried R, et al. A comparative assessment of endothelium from pseudophakic and phakic donor corneas stored in organ culture. Br J Ophthalmol 2002;86:400–3.z'$(e0}, 百拇医药
Lavery KT, McDermott ML, Ernest PH, et al. Endothelial cell loss after 4 mm cataract surgery. J Cataract Refract Surg 1995;21:305–8.z'$(e0}, 百拇医药
Liesegang TJ, Bourne WM, Ilstrup DM. Endothelial cell loss following cataract surgery. Am J Ophthalmol 1984;97:32–9.z'$(e0}, 百拇医药
Ravalico G, Tognetto D, Baccara F, et al. Corneal endothelial protection by different viscoelastics during phacoemulsification. J Cataract Refract Surg 1997;23:433–9.z'$(e0}, 百拇医药
Stocker FW, King EH, Lucas DO, et al. A comparison of two principles for evaluating corneal endothelial viability. Arch Ophthalmol 1959;47:772–82.z'$(e0}, 百拇医药
Panda A, Venkateshwarlu K, Angra SK, et al. Corneal changes in the corneal endothelial cell count as a function of age. Ind J Ophthalmol 1983;33:221–3.(A Panda M S Pangtey and P Sony)
We read with interest an article by Meier et al.1 No doubt, this is an exciting issue on donor tissue harvesting and is more meaningful for the developing countries, where there is paucity of the donor material and, as a corollary to this, more people with corneal blindness. Further, because of more awareness towards cataract surgery as a result of the Vision 2020 programme, more patients are getting operated for cataract with a posterior chamber intraocular lens insertion (PCIOL). This is more relevant because of the increase in lifespan, as a result of improved health care, worldwide./, http://www.100md.com
However, we would like to comment on few additional aspects which would make the subject more clear. It is known that small incision cataract surgery influences less endothelial dysfunction than conventional extracapsular cataract extraction with PCIOL insertion.2 Similarly, endothelial cell loss following cataract surgery is a gradual process and continues for 1–2 years.3 Therefore, it would have been better to understand, and analyse, the type of cataract surgery and the duration between cataract surgery and actual cornea retrieval. Though the better endothelial health in eyes with phacoemulsification was considered to be because of the shorter time taken with the procedure we feel, besides the time factor, the use of a high viscosity viscoelastic agent which is frequently used during phacoemulsification is responsible as it provides more endothelial protection and less chance of intraoperative corneoendothelial touch.4
The authors have further highlighted that prestorage endothelial evaluation was not done as it was extremely difficult in unstained corneas. But it might have been possible with 0.25% trypan blue staining, rather than alizarine red S, as this technique neither precludes clinical use nor its evaluation by other staining procedures.57k]](t0, 百拇医药
Finally, the authors have rightly emphasised three essential factors of endothelial evaluation: (i) endothelial cell density, (ii) percentage of hexagonality, (iii) coefficient of variation. Often, it is observed that endothelial status is commented only regarding cell count. This is more so for the developing countries where the endothelial specular microscope is not provided with the software by which the hexagonality and coefficient of variation can be calculated. Thus many good studies lose their authenticity owing to lack of this essential provision.6 We are grateful to the authors for throwing light on this aspect. On the basis of authors’ comments and our own experience we suggest that while placing an order for specular microscope, it is mandatory to include this important software.
The authors are also commended by suggesting another source of donor tissue for penetrating keratoplasty.z'$(e0}, 百拇医药
Referencesz'$(e0}, 百拇医药
Meier FM, Tschanz SA, Ganzfried R, et al. A comparative assessment of endothelium from pseudophakic and phakic donor corneas stored in organ culture. Br J Ophthalmol 2002;86:400–3.z'$(e0}, 百拇医药
Lavery KT, McDermott ML, Ernest PH, et al. Endothelial cell loss after 4 mm cataract surgery. J Cataract Refract Surg 1995;21:305–8.z'$(e0}, 百拇医药
Liesegang TJ, Bourne WM, Ilstrup DM. Endothelial cell loss following cataract surgery. Am J Ophthalmol 1984;97:32–9.z'$(e0}, 百拇医药
Ravalico G, Tognetto D, Baccara F, et al. Corneal endothelial protection by different viscoelastics during phacoemulsification. J Cataract Refract Surg 1997;23:433–9.z'$(e0}, 百拇医药
Stocker FW, King EH, Lucas DO, et al. A comparison of two principles for evaluating corneal endothelial viability. Arch Ophthalmol 1959;47:772–82.z'$(e0}, 百拇医药
Panda A, Venkateshwarlu K, Angra SK, et al. Corneal changes in the corneal endothelial cell count as a function of age. Ind J Ophthalmol 1983;33:221–3.(A Panda M S Pangtey and P Sony)