Kraig S. Bower

Corneal Biomechanics Following Epi-LASIK

PURPOSEnTo evaluate corneal biomechanical changes following epi-LASIK.nnnMETHODSnIn this prospective study of 51 patients, corneal hysteresis (CH), corneal resistance factor (CRF), and intraocular pressure (IOP) were assessed using the Ocular Response Analyzer (ORA, Reichert Technologies) preoperatively and at 1, 3, 6, and 12 months after epi-LASIK. Repeated measures analysis of variance (ANOVA) was used to compare changes over time (alpha=.05). Intraocular pressure was also measured by Goldmann applanation tonometry.nnnRESULTSnCorneal hysteresis decreased from 10.22±1.65 mmHg preoperatively to 8.17±1.25 mmHg at 1 month, 8.46±1.44 mmHg at 3 months, 8.63±1.31 mmHg at 6 months, and 8.53±1.49 mmHg at 12 months. Corneal resistance factor decreased from 10.01±1.80 mmHg preoperatively to 7.82±1.68, 8.03±1.85, 7.77±1.50, and 7.80±1.66 mmHg at 1, 3, 6, and 12 months, respectively. Repeated measures ANOVA showed a significant change over time for both CH and CRF (P<.0005). All measures of IOP changed significantly over time (P<.0005).nnnCONCLUSIONSnEpi-LASIK resulted in a significant change in CH and CRF postoperatively. Although some recovery occurred over time, CH, CRF, and IOP did not revert to preoperative levels.

Novel corneal phenotype in a patient with alport syndrome.

Purpose: To report the clinical and histopathologic findings of an unusual keratopathy, which may represent a new corneal dystrophy in a patient with Alport syndrome (ATS). Methods: A 59-year-old woman with longstanding diagnosis of autosomal recessive ATS was evaluated for progressively decreasing vision in the left eye. She had anterior lenticonus and cataract and central corneal stromal opacification with significant thinning and flattening bilaterally. She underwent penetrating keratoplasty and cataract extraction with posterior chamber intraocular lens implantation. We describe the light microscopic and ultrastructural findings from the cornea. Results: Histopathology of the corneal button revealed marked stromal thinning with decreased keratocytes. The endothelial cells were attenuated and focally lost. Immunohistochemical stains for cytokeratin were positive, findings consistent with posterior polymorphous dystrophy (PPMD). Transmission electron microscopy showed necrosis and a marked loss of keratocytes. Multilayering of the endothelium was consistent with PPMD, but mature desmosomes and microvilli were absent. In vivo confocal microscopy on the fellow eye showed linear hyporeflective bands at the level of Descemets membrane consistent with PPMD. In addition, there were fine linear changes in the deep stroma and diffuse hyperreflectivity of the mid and superficial stroma with lack of identifiable keratocytes throughout. Conclusions: We believe this to be the first reported case to demonstrate some histopathologic features of PPMD in ATS. However, the clinical, histopathologic, and ultrastructural characteristics are not typical of PPMD. This may represent a new phenotypic expression of PPMD or may be a distinct clinicopathologic dystrophy associated with ATS.

Mitochondrial myopathy presenting with segmental corneal oedema and retrocorneal membrane

Chronic progressive external ophthalmoplegia (CPEO) is a genetic disorder of mitochondrial DNA characterised by progressive ocular dysmotility and eyelid ptosis.1 Other ophthalmological manifestations of mitochondrial eye disease include optic atrophy and retinal pigmentary changes. There have also been several reports of corneal opacification associated with Kearns–Sayre syndrome and ophthalmoplegia-plus.2–5 Corneal decompensation secondary to exposure from lagophthalmos and absent Bell’s phenomenon has been reported in CPEO, but few have progressive peripheral corneal oedema.6,7 We describe a patient presenting initially with bilateral segmental corneal oedema, in whom the subsequent diagnosis of CPEO followed the corneal changes.nnA 38-year-old black woman with a diagnosis of primary ovarian failure presented with 5 years of bilateral progressive corneal oedema. Initial visual acuity was 20/60 …

Anterior segment measurements using digital photography: a simple technique.

Purpose. The purpose of this study is to describe a simple method of measuring anterior segment lesions from digital slit lamp images and confirm reliability of the technique. Methods. Ten reference photos were taken of a PD ruler, refocusing on the ruler for each photo. Using Adobe Photoshop, the number of pixels per millimeter squared (area) and 1 mm (linear) were recorded for each photo. An Excel spreadsheet was set up to convert pixels to millimeters and millimeters squared. Interrater reliability was determined by two observers who independently calculated the area of 69 epithelial defects. A Bland and Altman plot was used to demonstrate the agreement between the two doctors. Results. Interrater reliability was excellent as measured by an intraclass correlation coefficient (ICC 2,1) = 0.99. From the Bland and Altman plot it was determined that in 95% of cases, the area of the epithelial defect measured by provider 2 may be as much as 1.17 mm2 less than or 1.09 mm2 greater than that measured by provider 1. Conclusion. This simple method, which allows accurate measurements from digital images using common off-the-shelf software, is a valuable tool for clinical documentation as well as for research purposes.

Fabry disease and chemosis.

Purpose: To report the case of a patient with Fabry disease (FD) whose ocular presentation with chronic chemosis we feel is related to FD and to describe the conjunctival fluorescein angiographic findings. Methods: A 51-year-old male patient with FD on enzyme replacement therapy presented with 1-month chemosis and mild irritation in the left eye. Ocular examination revealed pronounced noninflammatory chemosis inferotemporally in the left eye with conjunctival tortuosity and microaneurysms bilaterally. There was mild corneal verticillata, spoke-like lens opacities, and retinal vascular tortuosity bilaterally, with no evidence of disc or macular edema. Evaluation revealed no systemic cause for his chemosis, including an orbital computerized tomography scan, which showed clear sinuses and no evidence of an intraorbital mass. Results: Conjunctival fluorescein angiography revealed rapid subconjunctival accumulation of dye in the involved eye but failed to demonstrate leakage from tortuous conjunctival vessels or microaneurysms. Conclusions: Although the pathology of chronic chemosis in patients with FD is as yet unknown, we believe that FD should be considered in the differential diagnosis of patients presenting with chronic chemosis of unknown etiology.

Ocular Diseases and Nonbattle Injuries Seen at a Tertiary Care Medical Center during the Global War on Terrorism

We retrospectively reviewed the records of 107 U.S. military personnel referred to the Walter Reed Army Medical Center ophthalmology service with eye diseases and nonbattle injuries diagnosed during Operation Enduring Freedom and Operation Iraqi Freedom. Ocular diseases and nonbattle injuries ranged from minor to vision-threatening, represented a broad variety of conditions, and required the expertise of a number of ophthalmic subspecialists. The most common diagnoses were uveitis (13.1%), retinal detachment (11.2%), infectious keratitis (4.7%), and choroidal neovascularization (4.7%). Eighty-four patients (78.5%) met Army retention standards and were returned to duty. Twenty patients (18.7%) were referred to a medical evaluation board, seven (6.5%) of whom failed to meet retention standards for eye and vision; the retention status of three patients (2.8%) remains to be determined.

The effect of moxifloxacin and gatifloxacin on long-term visual outcomes following photorefractive keratectomy.

PURPOSEnTo compare the effect of gatifloxacin and moxifloxacin on visual outcomes after photorefractive keratectomy (PRK).nnnMETHODSnThirty-five PRK patients were treated postoperatively with gatifloxacin (Zymar) in one eye and moxifloxacin (Vigamox) in the fellow eye. Postoperative regimens were otherwise identical. In a previous study (initial phase), we evaluated epithelial healing. In this study (second phase), we compared uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest spherical equivalent (MSE), and corneal haze at 6 months postoperatively for 32 patients using the Wilcoxon signed ranks test.nnnRESULTSnNo statistically significant difference was noted between eyes treated with Zymar and Vigamox in terms of UCVA, BSCVA, MSE, or corneal haze at 6 months postoperatively. Two (6%) Vigamox-treated eyes versus 0 (0%) Zymar-treated eyes lost one line of BSCVA from preoperative examination. Median UCVA and MSE were equivalent for both groups.nnnCONCLUSIONSnAt 6 months after PRK, there was no significant difference in visual outcomes with either antibiotic.

Corneal iron line following LASIK with epithelial ingrowth

Purpose: To report a new corneal iron line following keratorefractive surgery. Methods: Case report and review of the literature. A 51-year-old man developed epithelial ingrowth after otherwise uneventful LASIK surgery. The patient, satisfied with an uncorrected visual acuity of 20/25 and otherwise asymptomatic, declined to have his flap relifted to treat the ingrowth. Results: Six months postoperatively a corneal iron line was noted at the leading edge of the epithelial ingrowth. Vision remained stable. Conclusions: Epithelial iron lines have been reported with a number of conditions, including post-refractive procedures. This is the first report of an iron line associated with epithelial ingrowth following LASIK.

Effect of blast trauma and corneal foreign bodies on visual performance.

Purpose. To evaluate the effect of non-penetrating corneal foreign bodies secondary to explosive blasts on the visual performance of soldiers. Methods. In a prospective, non-interventional study subjective visual performance and objective optical quality of 11 injured eyes with retained corneal foreign bodies were compared with that of 11 normal controls. Visual performance measures consisted of best spectacle-corrected high-contrast visual acuity (HCVA), low-contrast (5%) visual acuity (LCVA), and contrast sensitivity (CS). LCVA was evaluated in two luminance levels (photopic and mesopic) and two glare conditions (with and without glare). Acuity measurements were scored using logMAR notation. Objective optical quality was assessed comparing total root mean square wavefront error (WFE) and percent higher order aberrations. Modulation transfer functions calculated from the wavefront maps were used to predict the results of the psychophysical contrast testing. Results. HCVA of injured eyes (M = −0.03) did not differ significantly (t(20) = 1.56, p = 0.13) when compared with controls (M = −0.09). However, visual performance of injured eyes (M = 0.33) was significantly worse than control eyes (M = 0.11) on photopic LCVA (t(20) = 4.16, p < 0.001), mesopic LCVA(M = 0.44 vs. M = 0.21, t(20) = 3.85, p = 0.001), mesopic LCVA with glare (M = 0.49 vs. M = 0.21, t(20) = 3.66, p = 0.002), and small letter CS (M = 0.25 vs. M = 0.90, t(20) = −6.6, p < 0.001). For a 6-mm pupil, mean absolute WFE attributed to higher order aberrations for the injured eyes was 0.86 &mgr;m and 0.59 &mgr;m for the control eyes. This difference was significant (t(20) = −2.15, p = 0.044). Conclusions. Although HCVA was no different than the normal controls, visual performance of the injured eyes was significantly worse in terms of LCVA and CS. On average, visual performance can be broadly predicted by the modulation transfer function derived from the subjects wavefront aberration map.

Scattered ultraviolet emissions during refractive surgery using a high-frequency, wavefront-optimized excimer laser platform

PURPOSE: To evaluate occupational ultraviolet (UV) exposure during photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) with the Allegretto Wave Eye‐Q 400 Hz excimer laser. SETTING: Walter Reed Center for Refractive Surgery, Washington, DC, USA. METHODS: Intraoperative UV measurements were performed during PRK with epithelial removal using an Amoils brush, PRK with epithelial removal using 20% ethanol, or femtosecond LASIK. A LaserStar power/energy meter with a silicone detector (model PD‐10) was used for the measurements. The maximum pulse energy 25.4 cm from the corneal surface was recorded for each surgical procedure. Measurements were evaluated using a worst‐case scenario for exposure of operating room personnel, and the results were compared with the occupational exposure limit set by the International Commission on Non‐Ionizing Radiation Protection. RESULTS: Measurements were taken during 15 cases of each procedure. The mean maximum exposure was 129.38 nJ/pulse ± 79.48 (SD) during brush PRK, 69.72 ± 68.80 nJ/pulse during ethanol PRK, and 29.17 ± 13.82 nJ/pulse during LASIK. The mean maximum exposure per eye was 0.085 mJ/cm2, 0.046 mJ/cm2, and 0.01 mJ/cm2, respectively. The worst‐case cumulative exposure during a heavy workday of 20 patients (40 eyes) was calculated at 3.92 mJ/cm2, 1.51 mJ/cm2, and 0.79 mJ/cm2 for brush PRK, ethanol PRK, and LASIK, respectively. CONCLUSION: Results indicate that the excimer laser platform used in the study may yield greater UV exposure than previous systems; however, the levels did not exceed occupational exposure limits. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.