Richard G. Lembach

Clinical Management of Keratoconus: A Multicenter Analysis

The clinical management of 746 eyes in 417 patients referred for keratoconus from January 1984 through January 1988 was retrospectively analyzed. In 357 patients, 554 eyes (74%) did not require surgery and were managed with contact lenses or spectacles, 156 eyes (21%) in 137 patients either underwent penetrating keratoplasty (PK) (140 eyes) or surgery was recommended (16 eyes), and 36 eyes (4%) in 34 patients underwent epikeratoplasty. Comparing baseline and final examination findings, the nonsurgical group showed a significant improvement in average best-corrected visual acuity from 20/30 to 20/25, the PK group from 20/70 to 20/25, and the epikeratoplasty group from 20/40 to 20/30. Average keratometry was unchanged in the nonsurgical group, but decreased by 10.7 diopters (D) for the PK group and 6.5 D for the epikeratoplasty group. Corneal cylinder was unchanged in the nonsurgical group, whereas there was a reduction of the percentage of eyes with indeterminant cylinder from 55 to 2% in the PK group and from 36 to 0% in the epikeratoplasty group. Previous contact lens history, best-corrected visual acuity of 20/50 or worse, and average keratometry of 55 D or greater at baseline were associated with a significant risk for PK. No baseline variables were associated with significant risk for epikeratoplasty, suggesting that this group was similar to the nonsurgical group, except for contact lens intolerance. The nonsurgical management of keratoconus continues to play a predominant role in the management of this disorder in a referral population.

CLMI The Cone Location and Magnitude Index

Purpose: To develop an index for the detection of keratoconic patterns in corneal topography maps from multiple devices. Methods: For development, an existing Keratron (EyeQuip) topographic dataset, consisting of 78 scans from the right eyes of 78 healthy subjects and 25 scans from the right eyes of 25 subjects with clinically diagnosed keratoconus, was retrospectively analyzed. The Cone Location and Magnitude Index (CLMI) was calculated on the available axial and tangential curvature data. Stepwise logistic regression analysis was performed to determine the best predictor(s) for the detection of keratoconus. A sensitivity and specificity analysis was performed by using the best predictor of keratoconus. Percent probability of keratoconus was defined as the optimal probability threshold for the detection of disease. For validation, CLMI was calculated retrospectively on a second distinct dataset, acquired on a different topographer, the TMS-1. The validation dataset consisted of 2 scans from 24 eyes of 12 healthy subjects with no ocular history and 4 scans from 21 eyes of 14 subjects with clinically diagnosed keratoconus. Probability of keratoconus was calculated for the validation set from the equation determined from the development dataset. Results: The strongest significant sole predictor in the stepwise logistic regression was aCLMI, which is CLMI calculated from axial data. Sensitivity and specificity for aCLMI on the development dataset were 92% and 100%, respectively. A complete separation of normals and keratoconics with 100% specificity and 100% sensitivity was achieved by using the validation set. Conclusions: CLMI provides a robust index that can detect the presence or absence of a keratoconic pattern in corneal topography maps from 2 devices.

Epidermal growth factor and insulin use in corneal preservation : results of a multi-center trial

Purpose: The ability of DexSol medium, supplemented with two growth factors, human epidermal growth factor (hEGF) and human insulin, to improve long-term endothelial survival after penetrating keratoplasty was evaluated in a multi-center, randomized, prospective, double-masked clinical trial. Methods: Donor cornea pairs, one stored in DexSol and the other in DexSol with hEGF (10 μg/ml) and human insulin (10 pug/ml) (ProCell), were transplanted into 105 pairs of recipients matched by diagnosis and procedure and followed postoperatively for graft and endothelial survival. Results: No primary donor failures occurred in either group. Graft clarity did not differ between the ProCell and DexSol groups at all postoperative periods: 3 months (98% versus 99%), 6 months (94% versus 98%), and 1 year (95% versus 97%), respectively. Postoperative complications (e.g., glaucoma, rejection) occurred with comparable frequencies in both groups. Mean endothelial cell loss did not significantly differ between the ProCell and DexSol groups at 3 months (5.7% versus 5.1%), 6 months (8.1 % versus 10.1 %), and 1 year (12.3% versus 15.6%), respectively. Similarly, there were no clinically and statistically significant differences in other endothelial morphometric parameters. Conclusions: The use of corneas stored in DexSol medium with added hEGF and insulin in corneal transplantation resulted in a safety and efficacy profile comparable with that observed in patients receiving DexSol-stored corneas; however, there were no clinically and statistically significant differences in postoperative endothelial morphometric parameters.

Use of contact lenses for management of keratoconus

This article describes use of contact lenses to manage patients with keratoconus. Fitting concepts, prefit evaluations, types of lenses, initial lens selection, and potential problems and solutions are discussed.

Simulation of machine-specific topographic indices for use across platforms

Purpose. The objective of this project is to simulate the current published topographic indices used for the detection and evaluation of keratoconus to allow their application to maps acquired from multiple topographic machines. Methods. A retrospective analysis was performed on 21 eyes of 14 previously diagnosed keratoconus patients from a single practice using a Tomey TMS-1, an Alcon EyeMap, and a Keratron Topographer. Maps that could not be processed or that contained processing errors were excluded from analysis. Topographic indices native to each of the three devices were recorded from each map. Software was written in ANSI standard C to simulate the indices based on the published formulas and/or descriptions to extend the functionality of The Ohio State University Corneal Topography Tool (OSUCTT), a software package designed to accept the input from many corneal topographic devices and provide consistent display and analysis. Twenty indices were simulated. Linear regression analysis was performed between each simulated index and the corresponding native index. A cross-platform comparison using regression analysis was also performed. Results. All simulated indices were significantly correlated with the corresponding native indices (p < 0.01), with a mean R2 of 0.84, ranging from 0.42 to 0.99. Cross-platform comparisons were nonsignificant for specific indices and devices. Conclusion. Topographic indices native to three devices were successfully simulated. Cross-platform comparisons may be limited for specific indices.

Unilateral pseudophakia and extended-wear aphakic contact lenses A comparative study in a single patient population

Twenty-nine patients who were pseudophakic in one eye and wearing a Permalens in the other eye were evaluated. Pseudophakic correction provided the patient with good, stable visual acuity, minimal risks, and an excellent long-term prognosis. Permalens aphakic correction also provided the patient with good, but fluctuating visual acuity. Risks such as deposit formation, tight lens syndrome, and corneal infections were not infrequently associated with the Permalens, and Permalens patients were also faced with the recurring cost of lens replacement. While both modalities of aphakic visual rehabilitation are acceptable, pseudophakia appears to provide the patient with better visual acuity, fewer risks, and lower financial costs in the long run.

Factitious bilateral crystalline keratopathy.

We report a case of bilateral factitious crystalline keratopathy in an 18-year-old man. Initial slit-lamp examination revealed corneal ulcers characterized by stromal infiltrates with intrastromal blue refractile crystals O.D. greater than O.S. Through careful history taking, the patient admitted to bilaterally injecting eyeshadow into the corneal stroma. The importance of maintaining a high index of suspicion in bilateral atypical corneal ulcers in patients without a history of trauma or contact lens exposure is essential. Discussion of the differential diagnoses and approach to therapy is included.

Normative database of donor keratographic readings in an eye-bank setting

PURPOSE: To generate a normative donor topographic database from rasterstereography images of whole globes acquired in an eye‐bank setting with minimal manipulation or handling. SETTING: Eye‐bank laboratory. METHODS: In a retrospective study, rasterstereography topographic images that had been prospectively collected in duplicate of donor eyes received by the Central Ohio Lions Eye Bank between 1997 and 1999 were analyzed. Best‐fit sphere (BFS) and simulated keratometry (K) values were extracted. These values were recalculated after application of custom software to correct any tilt of the mapped surfaces relative to the image plane. The mean value variances between right eyes and left eyes, between consecutive scans, and after untilting were analyzed by repeated‐measures analysis of variance and t tests (P≤.05). RESULTS: A keratographic database of 556 pair‐matched right and left eyes was generated. Normal distributions were observed in frequency histograms of each value (P>.05, Kolmogorov‐Smirnov). There was no difference between right and left eyes or consecutive scans (P>.05). The mean values changed when the images were tilt‐corrected (P<.05). The right eye BFS, Kflat, and Ksteep values of 42.03 diopters (D) ± 1.88 (SD), 42.21 ± 2.10 D, and 43.82 ± 2.00 D, respectively, increased to 42.52 ± 1.73 D, 43.05 ± 1.99 D, and 44.57 ± 2.02 D, respectively, after tilt correction. CONCLUSIONS: Keratometric parameter frequency distributions from the donor database of tilt‐corrected data were normal in distribution and comparable to parameters reported for normal eyes in a living population. These findings show the feasibility and reliability of routine donor‐eye topography by rasterstereography. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Analysis of photorefractive keratectomy (PRK) results at The Ohio State University

The Ohio State University (OSU) is one site of an FDA controlled investigational study to evaluate the safety and efficacy of excimer laser photorefractive keratectomy (PRK). This is a report of the current Phase III results at OSU for cases at 6 months post surgery as of 12/31/92.

Contamination by Nonfermentative Microorganisms in M-K and Organ Culture Media

The effect of nonfermentative microorganisms on the pH indicator phenol red used in McCarey-Kaufman (M-K) medium and Organ Culture medium was examined. Separate aliquots of M-K media and Organ Culture media were inoculated with cultures of known fermentative and nonfermentative bacteria. Phenol red accurately indicated the growth of fermentative bacteria at 37°C and 4°C by exhibiting a pH-sensitive change in color, but did not reveal nonfermentative bacterial growth. A different method of detection is necessary to identify the presence of nonfermentative bacteria in these media.