Leo J. Maguire

Corneal Topography of Early Keratoconus

We used a corneal topography analysis system to evaluate nine eyes of seven patients in whom the diagnosis of keratoconus was suspected. There was no slit-lamp evidence of the condition. In seven of nine eyes a cone was identified. Large amounts of corneal distortion were seen in selected patients even though they had excellent spectacle-corrected visual acuity and little or no distortion of the keratometer mires. These findings suggest that corneal topography analysis systems are useful in the detection and description of corneal irregularity in the early stages of keratoconus. The radial keratotomy surgeon should be aware that normal results on slit-lamp examination and normal keratometry and refractive data do not rule out the presence of early keratoconus.

Effect of myopic laser in situ keratomileusis on epithelial and stromal thickness: a confocal microscopy study.

PURPOSE To determine changes in central epithelial and stromal thickness in human corneas in vivo after laser in situ keratomileusis (LASIK). DESIGN Prospective, nonrandomized, comparative trial. PARTICIPANTS Eighteen eyes of 12 patients received LASIK (performed using the VISX Star laser [VISX, Santa Ana, CA]) with a planned 180- micro m flap (created using an automated Hansatome microkeratome [Bausch & Lomb, Irvine, CA]) to correct refractive errors between -2.0 diopters (D) and -11.0 D. METHODS Corneas were examined by using confocal microscopy in vivo before LASIK and at 1 week and 1, 3, 6, and 12 months after LASIK. Epithelial thickness was the distance between images of the surface epithelium and subbasal nerve plexus or, when nerves were not visible, the subbasal peak (if present in the light intensity profile). Total flap thickness was the distance between images of the surface epithelium and interface debris (or peak), and total stromal thickness was the distance between images of the most anterior keratocytes and endothelium. MAIN OUTCOME MEASURES Corneal epithelial and stromal thickness. RESULTS Epithelial thickness before LASIK was 46 +/- 5 micro m (mean +/- standard deviation) and increased 22% by 1 month after LASIK (56 +/- 5 micro m; P = 0.01). Thereafter, epithelial thickness did not change, but remained thicker at 12 months after LASIK (54 +/- 8 micro m) than before LASIK (P = 0.02). Total flap thickness at 1 month after LASIK was 160 +/-28 micro m and did not change thereafter. Changes in total stromal thickness between 1 and 12 months after LASIK were not significant. CONCLUSIONS The central corneal epithelium was thicker in the first year after LASIK than before LASIK. There was no change in central stromal thickness between 1 month and 12 months after LASIK.

The effect of corneal light scatter on vision after descemet stripping with endothelial keratoplasty

OBJECTIVE To establish an association between corneal light scatter and vision after Descemet stripping with endothelial keratoplasty (DSEK). METHODS Twenty eyes of patients with Fuchs endothelial dystrophy were examined before and at 1, 3, and 6 months after DSEK in a prospective study. Main outcome measures were high-contrast best-corrected visual acuity, intraocular forward light scatter, and corneal backscatter. RESULTS One eye was excluded because of endothelial graft failure within 1 month. Best-corrected visual acuity improved at 3 months after DSEK (mean [standard deviation], 0.31 [0.20] logarithm of the minimum angle of resolution [logMAR]; Snellen equivalent, 20/41) relative to before DSEK (0.46 [0.26] logMAR; Snellen equivalent, 20/58; P = .03). Posterior corneal backscatter decreased 1 month after DSEK (P < .001), but backscatter from the anterior, middle, and posterior cornea did not return to normal by 6 months (P < or = .02). At 6 months, best-corrected visual acuity correlated with recipient age (r = 0.84, P < .001) and with intraocular forward light scatter (r = 0.67, P < .001); forward light scatter also correlated with recipient age (r = 0.67, P < .001). CONCLUSIONS Six months after DSEK, corneal light scatter remained greater in eyes with Fuchs endothelial dystrophy than in normal eyes and correlated with recipient age and visual acuity. Recipient age might be the best preoperative predictor of vision after DSEK.

Identifying Progression of Subclinical Keratoconus by Serial Topography Analysis

We performed serial slit-lamp examinations and topography analysis on a patient whose initial topographic map suggested a diagnosis of keratoconus to us but which others interpreted as normal topography. Topography analysis documented cone progression during a two-year period. The initial map showed a cone apex power of 44.5 diopters located 2.1 mm inferior to the vertex normal. An oblong-shaped area of maximum power was surrounded by concentric bands of lower power. Corneal surface power ranged from 41.5 to 44.5 diopters. Two years later cone apex power increased to 51.0 diopters, and the patient developed a Fleischers ring, Vogts striae, and mild visual aberration. Our findings suggest the use of topography analysis systems in documenting subclinical cone progression. Topography systems may be a useful tool in the study of the true incidence and natural progression of subclinical keratoconus.

Keratocyte density of central human cornea after laser in situ keratomileusis

PURPOSE To determine changes in keratocyte density in the first year after laser in situ keratomileusis (LASIK). DESIGN Prospective interventional cohort study. METHODS Seventeen eyes of 11 patients received LASIK with a planned 180-microm flap to correct refractive errors between -2.0 diopters and -11.0 diopters. Images of the full-thickness cornea were obtained by using confocal microscopy in vivo before LASIK and at 1 week, 1, 3, 6, and 12 months after LASIK. Bright objects (that resembled keratocytes) in images without motion blur were manually counted by one observer. Cell densities were determined in anterior and posterior halves of the stromal flap, anterior and posterior halves of the layer 100 microm-thick immediately deep to the ablation (retroablation layer), and in the posterior third of the stroma. The region of stroma that was ablated (as measured 1 month after LASIK) was omitted from the preoperative analysis. RESULTS Keratocyte density in the anterior flap was 28,978 +/- 5849 cells/mm(3) (mean +/- SD) pre-LASIK, and was decreased at all postoperative examinations, but the difference was not significant until 12 months after LASIK (22% decrease). Keratocyte densities in the posterior flap were 20,397 +/- 4215 cells/mm(3) pre-LASIK and were decreased by 20%-40% at all postoperative examinations 1 week to 1 year after LASIK. Keratocyte densities in the anterior half of the retroablation layer were 16,605 +/- 3595 cells/mm(3) pre-LASIK and decreased by 16%-30% between 3 and 12 months after LASIK. Keratocyte densities in the posterior half of the retroablation layer and posterior stroma did not change. CONCLUSIONS Keratocyte densities in the posterior flap and anterior retroablation layer (regions adjacent to the lamellar cut) decrease at 1 week and 3 months, respectively, after LASIK and remain decreased in these regions at 12 months after LASIK. In the anterior flap, keratocyte density decreases 1 year after LASIK. The long-term effects of these cellular deficits, if any, require further study.

A computer model for the evaluation of the effect of corneal topography on optical performance

We developed a method that models the effect of irregular corneal surface topography on corneal optical performance. A computer program mimics the function of an optical bench. The method generates a variety of objects (single point, standard Snellen letters, low contrast Snellen letters, arbitrarily complex objects) in object space. The lens is the corneal surface evaluated by a corneal topography analysis system. The objects are refracted by the cornea by using raytracing analysis to produce an image, which is displayed on a video monitor. Optically degraded images are generated by raytracing analysis of selected irregular corneal surfaces, such as those from patients with keratoconus and those from patients having undergone epikeratophakia for aphakia.

Host and Graft Thickness after Descemet Stripping Endothelial Keratoplasty for Fuchs Endothelial Dystrophy

PURPOSE To determine relationships between vision, forward scatter, and total corneal and graft thicknesses after Descemet stripping endothelial keratoplasty (DSEK). DESIGN Prospective, cohort study. METHODS Forty-four eyes with Fuchs endothelial dystrophy were examined before and at 1, 3, 6, and 12 months after DSEK; all eyes were pseudophakic after surgery. Central total corneal and graft thicknesses were measured using confocal microscopy. Best-corrected high-contrast visual acuity (BCVA) was measured using the electronic Early Treatment Diabetic Retinopathy Study protocol, and forward light scatter was measured using a straylight meter. RESULTS Total corneal thickness was 610 ± 50 μm (mean ± standard deviation) before DSEK, increased to 680 ± 74 μm by 1 month after DSEK (P < .001), and stabilized at 660 ± 68 μm by 3 months after DSEK (P = .03 vs 1 month). Graft thickness was 170 ± 57 μm at 1 month, decreased to 157 ± 49 μm by 3 months (P = .004), and then remained stable through 12 months (156 ± 51 μm; P = .99 vs 3 months). BCVA was 0.44 ± 0.21 logarithm of the minimal angle of resolution (logMAR) units (Snellen equivalent, 20/55) before DSEK, improved to 0.26 ± 0.20 logMAR units (Snellen equivalent, 20/36) by 3 months (P < .001), and improved to 0.16 ± 0.16 logMAR units (Snellen equivalent, 20/29) at 12 months (P < .001 vs 3 months). BCVA and forward light scatter did not correlate with corneal or graft thickness after DSEK. CONCLUSIONS Stromal edema resolves by 3 months after DSEK for Fuchs dystrophy, whereas visual acuity continues to improve through 12 months. Thicker corneas and grafts are not associated with worse visual acuity or increased forward scatter.

Jupiter scleral lenses in the management of chronic graft versus host disease.

Objectives. To describe the use of the Jupiter scleral contact lens (Medlens Innovations, Front Royal, VA or Essilor Contact Lens, Inc., Dallas, TX) in the management of ocular manifestations of chronic graft versus host disease (cGVHD). Methods. This study is a retrospective case series. Five consecutive patients with severe keratoconjunctivitis sicca (KCS) associated with cGVHD that could not be adequately managed with conventional therapy were evaluated for scleral contact lens wear between January and December 2007. All patients were evaluated with lenses from the standard 18.2 mm Jupiter B diagnostic fitting set. If lenses of standard design failed to provide adequate fit, custom lenses were designed. Three outcome measures were evaluated: the patient’s ability to tolerate and successfully handle the lenses, improvement in symptoms of KCS, and improvement in visual acuity. Results. All 5 patients (10 eyes) were successfully fit with Jupiter scleral lenses. Six eyes of 3 patients were successfully fit with lenses of standard design. Standard parameters were altered to achieve adequate fit in 4 eyes of 2 patients. All patients reported subjective improvements in comfort with Jupiter scleral lenses, and best-corrected vision improved in 7 of the 10 eyes fit within the first several months of contact lens wear. The remaining 3 eyes maintained the visual acuity measured before scleral lens wear (20/20 in 2 eyes, 20/40 in 1 eye). Duration of follow-up ranged from 4 to 14 months. Conclusions. Jupiter scleral lenses can relieve symptoms of KCS and may improve vision in patients with cGVHD.

Corneal haze determined by confocal microscopy 2 years after descemet stripping with endothelial keratoplasty for fuchs corneal dystrophy

OBJECTIVE To quantify corneal light scatter and its relationship to vision after Descemet stripping with endothelial keratoplasty (DSEK). METHODS Eyes with Fuchs corneal dystrophy were examined before and 1, 3, 6, 12, and 24 months after DSEK. Outcome measures were high- and low-contrast visual acuity, contrast sensitivity, and forward light scatter. Corneal reflectivity (backscatter), expressed in scatter units (SU), was quantified using in vivo confocal microscopy. RESULTS Comparing 49 study eyes with 35 normal eyes, the mean (SD) corneal subepithelial layer was more reflective than normal before (2325 [613] vs 1208 [287] SU, P<.001) and through 24 months after DSEK (1760 [432] SU, P<.001). Interface reflectivity remained higher than in normal stroma through 24 months (1228 [287] vs 827 [188] SU, P<.001). At 1 year, forward light scatter correlated with subepithelial reflectivity (r=0.28, P=.01) but not interface reflectivity. Recipient age was correlated with improvement in subepithelial reflectivity at 12 months (r=–0.41, P=.01, 34 eyes) and 24 months (r=–0.36, P=.02, 26 eyes) after DSEK, and the improvement of subepithelial haze in eyes of participants aged 62 years or younger was correlated with improvement in forward light scatter at 12 months (r=0.52, P=.008) and 24 months (r=0.62, P=.004). CONCLUSIONS In Fuchs corneal dystrophy, the corneal subepithelial region is a more important source of forward light scatter than the DSEK interface. Subepithelial haze improves more in younger patients and is associated with improvement in forward light scatter. CLINICAL RELEVANCE Visual function after DSEK is affected by residual haze in the anterior host cornea more so than the surgical interface. Haze, which likely is experienced as glare disability, improves after surgical intervention but improves more in younger patients.

Comparison of Chen Medium and Optisol-GS for human corneal preservation at 4°C: Results of transplantation

Purpose. To compare results after transplantation of donor corneas stored in Chen Medium (containing &bgr;-hydroxybutyrate without sodium bicarbonate or chondroitin sulfate) to corneas stored in Optisol-GS medium (containing sodium bicarbonate and 2.5% chondroitin sulfate). Methods. We performed 32 consecutive penetrating keratoplasties with donor corneas stored at 4°C in either Chen Medium or Optisol-GS by random assignment. Corneal thickness measurements were made at 1 day, 1 week, 3 weeks, 2 months, and 1 year postkeratoplasty. Specular microscopic images of the donor endothelium were obtained at the beginning of storage and 2 months and 1 year postkeratoplasty. The percentage of intact epithelium 1 day after keratoplasty and the graft epithelialization time were estimated by the surgeons. Donor rim cultures were performed. Results. No statistically significant differences in corneal thickness or endothelial cell loss between the corneas stored in the two media were found at any time, although differences of less than 12% cell loss or 0.09-mm thickness at 2 months or less than 25% cell loss or 0.10-mm thickness at 1 year could not be excluded with 90% certainty in this small series. The mean percentages of intact graft epithelium on day 1, 64% for Chen Medium and 65% for Optisol-GS, were not significantly different. Endothelial cell density 2 months postkeratoplasty was significantly decreased for corneas stored in both media. Endothelial cell loss at 2 months was directly correlated with storage time in both media. Conclusions. After keratoplasty, no statistically significant differences in corneal thickness, epithelial survival, and endothelial cell loss were found between corneas stored in Chen Medium and Optisol-GS. Endothelial cell loss at 2 months was significantly correlated with storage time in both media.