Theodore P. Werblin

Epikeratophakia for the Treatment of Keratoconus

We have modified the technique of epikeratophakia to produce flattening of the keratoconus cornea and facilitate contact lens or spectacle correction of visual acuity. The epithelium was removed from the recipient cornea, and an epikeratophakia graft of uniform thickness was sutured tightly in place. The graft flattened the cone and markedly decreased the amount of irregular astigmatism. After surgery, our six patients have shown reduced myopia and cylinder and have little, if any, of the irregular astigmatism characteristic of keratoconus. These results are preliminary, and only long-term study of these and other similar cases can establish the safety and efficacy of this procedure.

Long-Term Endothelial Cell Loss Following Phacoemulsification: Model for Evaluating Endothelial Damage After Intraocular Surgery

BACKGROUND Newer concepts of phakic intraocular lens (IOL) surgery present concerns as to their long-term deleterious effect on the endothelium. We examine the behavior of the endothelium for up to 6 years following uneventful phacoemulsification surgery, to establish a baseline for what might be an acceptable level of endothelial cell loss due to intraocular surgical trauma. METHODS Ninety-three eyes undergoing phacoemulsification surgery who had multiple endothelial specular microscopy examinations for up to 6 years were examined. Central endothelial specular photomicrographs were analyzed in all cases and the percent of endothelial cell loss as a function of time was calculated. Cell density calculations were corrected for the normal endothelial cell loss as a function of age. RESULTS Routine uncomplicated phacoemulsification surgery demonstrated a 9% endothelial cell loss 1 year postoperatively. This is in marked contrast to the 16% average endothelial cell loss cited in the literature after phakic AC-IOL surgery. In general, anterior chamber IOL surgery following cataract removal compares unfavorably to posterior chamber IOL insertion long term (20% cell loss versus 12% cell loss). CONCLUSIONS A model is proposed to look at the rate of endothelial cell loss that would be significant enough to create the threat for corneal edema long term following refractive intraocular surgery in young patients. Suggestions for critical comparisons between the observed endothelial aging seen with phakic IOLs and values for more routine IOL surgery are proposed to predict the long-term threat for endothelial cell loss and corneal decompensation, which might result many years after phakic refractive IOL surgery.

The Casebeer System for Predictable Keratorefractilove Surgery: One-year Evaluation of 205 Consecutive Eyes

PURPOSE This study documents the results of current radial keratotomy (RK) surgical technology, using the Casebeer keratorefractive system. These results are contrasted to those of the Prospective Evaluation of Radial Keratotomy (PERK) keratorefractive system, developed approximately 12 years ago. METHODS Two hundred five consecutive surgical procedures were examined, which was the first year of experience with RK for one of the authors (TPW). All procedures fit within the Casebeer nomograms. Enhancement procedures were performed following the Casebeer system nomograms. RESULTS Follow-up for 100% of patients was achieved. Postoperative cycloplegic refractions yielded an average of +0.27 +/- 0.58 diopters (D) of residual refractive correction (range, -0.88 to +2.50 D). One year postoperatively, 20/25 or better uncorrected visual acuity was achieved in 86% of patients and 20/40 or better uncorrected visual acuity was achieved in 99% of patients. Bothersome but not incapacitating side effects, such as glare, starbursting, and fluctuating vision, have been commonly observed with RK. CONCLUSION The Casebeer system for keratorefractive surgery, which is easy to learn, can yield an extremely accurate surgical result. The major reason for increased accuracy compared with the PERK system is the surgeons ability to titrate the primary surgical procedure with enhancement operations. Although RK is by no means a perfect surgical technique, side effects tend to be relatively minimal, and patient satisfaction tends to be extremely high.

Do three-piece PMMA IOLs rotate after implantation in the capsular bag ?

BACKGROUND With the current interest in toric intraocular lenses (IOLs), it is critical to establish whether these implants rotate following cataract surgery. If there is continual rotation of the implant with capsular bag contraction, then the orientation of the astigmatic correction would be unstable and thus not clinically useful. METHODS Twenty-eight eyes were followed for up to 6 months postoperatively. These consecutive eyes were selected on the basis of demonstrating adequate dilation following surgery, such that the points of haptic to optic insertion could be visualized with the slit-lamp microscope. Sequential photographs and comparisons of the orientation of the lenses postoperatively were performed. RESULTS With the exception of one lens implant, none of the 28 IOLs demonstrated significant rotation. Of the 16 eyes followed for 6 months, none demonstrated rotation of greater than 4 degrees, which was within experimental error. CONCLUSIONS Continued rotation of PMMA IOLs following implantation in the capsular bag seldom occurs. Thus, the concept of toric IOLs appears to be quite usable.

Epikeratophakia: The surgical correction of aphakia. II. Preliminary results in a non-human primate model

We have developed a new form of refractive surgery, epikeratophakia, in which a disc of donor corneal tissue is lathed to a specific dioptric power and sutured on top of the recipients cornea after the recipient epithelium has been removed. The optical correction obtained with epikeratophakia should be similar in quality to that of a contact lens, but would be permanent and would require no maintenance. A non-human primate model was used to test the predictability, stability, and clarity of epikeratophakia grafts. After surgery, the grafts did not always re-epithelialize readily; this problem has been solved with the use of a small, steep, soft bandage contact lens. For the nine month period of this study, the epikeratophakia grafts have remained clear and the curvatures of the anterior surfaces have remained constant. However, the actual visual potential of these grafts can be evaluated only by a controlled clinical study in humans.

Initial human experience with Permalens myopic hydrogel intracorneal lens implants.

BACKGROUND Previous nonhuman primate experimentation has demonstrated the successful use of Permalens hydrogel intracorneal lens implants for the correction of hyperopic and myopic refractive errors. This article documents the first human experience with myopic Permalens hydrogel intracorneal lens implants. METHODS In this article, we report an 18-month follow up on five patients implanted with minus power hydrogel intracorneal lenses. All surgery and follow-up examinations were performed in Bogota, Columbia. The mean preoperative spherical refraction was -14.00 +/- 5.00 diopters (range, -9.5 to -19.00 D). RESULTS Corrections of up to 13.00 D were achieved. Corrections deviated from the predicted correction by a mean of -5.00 +/- 2.10 D (range, -2.80 to -8.00 D). No significant surgical or postoperative complications were noted. Visual recovery was rapid, usually achieving maximum acuity within 1 month. CONCLUSIONS Successful myopic refractive changes were accomplished in all five human subjects. The major problem with the study to date has been a significant undercorrection of the preoperative refraction. We anticipate that further empirically derived relationships between hydrogel lens power and refractive change will allow a more accurate prediction of refractive result. Also, the ability to surgically interchange myopic hydrogel inlays should allow correction of any residual refractive errors.

Eight years experience with Permalens® intracorneal lenses in nonhuman primates

BACKGROUND For the past 8 years, three independent laboratories have been researching the biocompatibility and performance of Permalens intracorneal lens implants in the corneas of nonhuman primates. Both myopic and hyperopic corrections have been achieved. This article describes the evolution of the intracorneal lens design and manufacturing process. METHODS During this time period, 63 surgeries were performed on various species of nonhuman primates. Follow-up examination extended between 30 months and 8.2 years. Objective measures of refractive performance, as well as biocompatibility were made using slit lamp, retinoscopy, autorefractor, specular microscope, etc. Additionally, histopathology was performed on many of the specimens, both acute and chronic. RESULTS Surgically successful implants were achieved in between 60% and 100% of eyes in the various series of lens implants outlined in the article. Levels of contamination in the preparation of hydrogels were felt to be responsible for many of the surgical failures. The removal of silicone and other contaminants seems to have significantly improved the biocompatibility of these materials within the cornea. The major histopathological finding was that there appeared to be some epithelial thinning over the implants, but in general excellent biocompatibility was obtained over the 8-year period outlined in this paper. CONCLUSIONS Although extensive studies of biocompatibility have been completed, the future of the performance of these materials remains to be proven in the human subject. Additionally, empirical relationships between lens implant power and refractive results will have to be determined in humans, prior to their general clinical usage.

The Use of Slow-Release Artificial Tears in the Long-Term Management of Keratitis Sicca

Fifty-eight patients with keratitis sicca were enrolled in a long-term study to test the effectiveness of slow-release artificial tears (SRAT). The average follow up period of 39 weeks, with a range of 9 to 136 weeks. Forty-six (79%) are still being followed. Almost all of these patients have had marked relief from their symptoms and a significant decrease in corneal abnormalities. The high rate of success in this patient population was probably due in large part to patient selection, that is, patients were quite symptomatic and had been symptomatic for an average of three years prior to entering this study. For patients with fairly severe keratitis sicca for whom artificial tears alone are insufficient, SRAT offers an important and practical means of markedly decreasing symptoms and improving vision with ony minor side effects.

The Cornea Press: Restoring Donor Corneas to Normal Dimensions and Hydration Before Cryolathing

The shaping of swollen, abnormally hydrated donor corneal tissue on the cryolathe for use in keratorefractive surgery yields lenticules of insufficiently predictable dioptric powers. The irregular nature of this abnormal hydration precludes the use of mathematical compensating factors. To improve control over the shape of the lenticule, we have developed a cornea press which restores normal hydration and dimensions to the donor tissue by mechanical dehydration.

Fetal Adenoma of the Pigmented Ciliary Epithelium Associated with Persistent Hyperplastic Primary Vitreous

A 1.5-year-old girl presented with a peripheral iris mass. When the girl was 3 years old, the lesion was excised after it had manifested significant growth. A stalk of fibrovascular tissue was noted to extend from the lesion to the optic disc. Histopathologically, the tumor was a well-circumscribed, pigmented ciliary body adenoma. Electron microscopy revealed characteristic neuroepithelial melanosomes, distinct from those of choroidal melanocytes, and occasional annulate lamellae. A fibrovascular membrane extended over the tumor surface and was adherent to lens capsule. The association of this adenoma with a persistent stalk of primary vitreous indicates a congenital origin of this tumor. Both adenoma and adenocarcinoma of the pigmented and nonpigmented ciliary epithelium tend to be disorders of adults. The authors report the youngest presentation of a pigment epithelium adenoma, the only well-documented case associated with persistent hyperplastic primary vitreous, and the only documentation of annulate lamellae in a ciliary body tumor.