The U.S. Army Surface Ablation Study: comparison of PRK, MMC-PRK, and LASEK in moderate to high myopia.

PURPOSE: To compare visual outcomes following photorefractive keratectomy (PRK), PRK with mitomycin C (MMC-PRK), and LASEK in moderate and high myopia in military personnel. METHODS: This prospective, randomized contralateral eye study included 167 patients 21 years or older with manifest spherical equivalent -5.99 ± 1.40 diopters (D) (range: -3.88 to -9.38 D) randomized to either MMC-PRK or LASEK treatment in their dominant eye and conventional PRK without MMC in the fellow eye. All procedures were performed using the LADARVision 4000 Excimer Laser System (Alcon Surgical Inc., Ft. Worth, TX). High- and low-contrast visual acuities, manifest refraction, endothelial cell count, and corneal haze were evaluated up to 12 months postoperatively. RESULTS: At 12 months postoperatively, visual outcomes were comparable among the treatment groups. Corneal haze of any grade was less common in MMC-PRK compared to PRK at 1 month (21.4% vs 31.0%; P < .01) and 3 months (12.8% vs 35.9%; P = .03) postoperatively; it was also less common in MMC-PRK compared to LASEK at 1 month (21.4% vs 55.9%; P < .01), 3 months (12.8% vs 42.4%; P < .01), and 6 months (12.2% vs 36.4%; P = .03) postoperatively. Haze rate (grade 0.5 or higher) was comparable between LASEK and PRK. Clinically significant haze (grade 2 or higher) developed after PRK (4 eyes) and LASEK (2 eyes), but not after MMC-PRK. CONCLUSIONS: MMC-PRK showed some benefits in minimizing corneal haze formation. One year after surgery, there was no discernible difference in the postoperative refractive outcomes among the three methods.

Visual outcomes after Epi-LASIK and PRK for low and moderate myopia.

PURPOSE: To evaluate visual outcomes following epi-LASIK compared to photorefractive keratectomy (PRK). METHODS: Of a total 294 patients aged ≥21 years, 145 (290 eyes) underwent epi-LASIK and 149 (298 eyes) underwent PRK for low to moderate myopia or myopic astigmatism. Epi-LASIK was performed with the Amadeus II epikeratome (Abbott Medical Optics) and PRK with the Amoils rotary epithelial brush (Innovative Excimer Solutions). All ablations were performed using the same excimer laser system. Outcome measures included intraoperative complications, corneal reepithelialization, postoperative pain, uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), corrected distance visual acuity (CDVA), corneal haze, and quality of vision. RESULTS: Mean preoperative MRSE was -2.97±1.19 diopters (D) for epi-LASIK versus -2.95±1.06 D for PRK. Complete reepithelialization was achieved by postoperative day 4 in 46.9% of epi-LASIK eyes versus 92.4% of PRK eyes, with superior UDVA at postoperative day 1 in the PRK group (P=.002). Using Fisher exact test, a significantly higher percentage of epi-LASIK eyes compared to PRK eyes achieved 20/15 or better at 1 month (25.8% vs 17.8%, P=.031), 3 months (62.3% vs 49.3%, P=.004), 6 months (77.1% vs 57.9%, P<.001), and 12 months (75.9% vs 61.9%, P=.002). A change in MRSE >0.50 D occurred in 8.4% of epi-LASIK eyes within the 3- and 12-month interval versus 17.7% of PRK eyes (P=.04). No differences were noted between the two procedures in CDVA or clinically significant haze. CONCLUSIONS: Epi-LASIK showed superior refractive efficacy and stability but required more time for wound healing, resulting in inferior early visual outcomes and a tendency to overcorrect higher refractive errors compared to PRK. Both treatments were safe and comparable in terms of pain and haze formation.

Tumor necrosis factor-alpha (TNF-α) levels in aqueous humor of primary open angle glaucoma.

PURPOSE: Tumor necrosis factor alpha (TNF-α), a macrophage/monocyte derived pluripotent cytokine is associated with tissue ischemia, neuronal damage and remodeling. The physiological level of TNF-α in aqueous humor of normal and glaucomatous eyes is unknown. In this study, we evaluated the TNF-α levels in aqueous in patients with primary open angle glaucoma (POAG) and compared them to controls. METHODS: 50-100 µL of undiluted aqueous humor samples were obtained from eyes of 32 POAG patients who underwent cataract extraction, trabeculectomy or aqueous shunt implantation. Controls were obtained from 32 normal subjects who underwent routine cataract surgery. TNF-α levels were quantified using singleplex bead immunoassay analysis. RESULTS: The average TNF-α level in POAG samples was 2.72 ± 1.5 pg/mL (mean ± SD). The average TNF-α level in normal samples was 1.59 ± 0.46 pg/mL (mean ± SD). Significant increase of TNF-α levels in POAG samples was noted in comparison to normal samples (P < 0.001). CONCLUSION: TNF-α levels are elevated in aqueous in patients with POAG compared to normal subjects based on highly sensitive Luminex(®) bead immunoassay and may be a reliable biomarker in the progression of glaucoma.

Corneal biomechanics following epi-LASIK.

PURPOSE: To evaluate corneal biomechanical changes following epi-LASIK. METHODS: In 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. RESULTS: Corneal 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). CONCLUSIONS: Epi-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.

Oral gabapentin for photorefractive keratectomy pain.

PURPOSE: To compare the efficacy of oral gabapentin versus placebo for the control of severe pain after photorefractive keratectomy (PRK). SETTING: Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, DC, USA. DESIGN: Randomized masked clinical trial. METHODS: This single-center clinical trial comprised active-duty United States Army soldiers aged 21 years or older having bilateral PRK for myopia with or without astigmatism. Patients received gabapentin 300 mg or placebo 3 times daily for 7 days beginning 2 days before and continuing for 4 days after surgery. Current and maximum pain levels were assessed using the Visual Analog Pain scale 2 hours after surgery and then daily on days 1 through 4. Repeated-measures analysis of variance (ANOVA) was used to compare the current and maximum pain scores over time between the gabapentin group and the placebo group. The Fisher exact test was used to determine whether there was a difference in severe pain (>7/10) between the 2 groups. RESULTS: Forty-two patients received gabapentin and 41 patients, placebo. The repeated-measures ANOVA showed no significant difference between the 2 groups in current pain (P = .84) or in maximum pain over time (P = .35). Oxycodone-acetaminophen use in the gabapentin group was significantly higher than in the placebo group 1 day postoperatively (P = .034). CONCLUSION: When added to a standardized postoperative pain regimen, gabapentin use led to no additional improvement in PRK pain control compared with a placebo at the dose and the time intervals tested.

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/cm(2), 0.046 mJ/cm(2), and 0.01 mJ/cm(2), respectively. The worst-case cumulative exposure during a heavy workday of 20 patients (40 eyes) was calculated at 3.92 mJ/cm(2), 1.51 mJ/cm(2), and 0.79 mJ/cm(2) 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.

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 Descemet's 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.

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.

Effect of brimonidine tartrate 0.15% on night-vision difficulty and contrast testing after refractive surgery.

PURPOSE: To evaluate the efficacy of brimonidine tartrate ophthalmic solution 0.15% in patients with night-vision difficulties after laser refractive surgery. SETTING: Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, District of Columbia, USA. METHODS: Six patients with significant night-vision complaints after refractive surgery were enrolled in this study after other treatable causes of night-vision difficulty such as residual refractive error and dry eye were excluded. Low-contrast visual acuity (LCVA) over a range of contrasts (1.25% to 25%) and small letter contrast sensitivity were tested at photopic (100 cd/m(2)) and mesopic (1 cd/m(2)) luminance levels, with and without a standard glare source. Testing was performed before brimonidine tartrate ophthalmic solution 0.15% was administered. Measurements were repeated 1 hour and 1 month after the use of brimonidine tartrate. RESULTS: One hour after using brimonidine tartrate 0.15% solution, patients had significant improvement in LCVA, LCVA with glare, and contrast sensitivity. After 1 month of treatment, all 6 patients reported subjective improvement in night vision and there was a significant difference in performance in mesopic LCVA and mesopic LCVA with glare. The mean pupil size before administration of brimonidine tartrate ophthalmic solution 0.15% was 6.44 mm +/- 1.11 (SD). Pupil size 1 hour after instillation had decreased to 4.53 +/- 1.27 mm and at 1 month had increased to 6.50 +/- 0.94 mm. CONCLUSION: Brimonidine tartrate ophthalmic solution 0.15% improved contrast sensitivity and acuity and decreased night-vision difficulty for up to 1 month in patients with significant complaints after refractive surgery.

Effects of lotrafilcon A and omafilcon A bandage contact lenses on visual outcomes after photorefractive keratectomy.

PURPOSE: To evaluate postoperative healing between bandage contact lenses with high and low oxygen permeability in patients having photorefractive keratectomy (PRK). SETTING: Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, DC, USA. METHODS: This retrospective study compared patients receiving a high-oxygen-transmission bandage contact lens (Focus Night & Day [N&D], Ciba Vision; n = 92) and those receiving a low-oxygen-transmission lens (Proclear, Cooper Vision; n = 114) after PRK. Visual outcomes, safety, and efficacy were assessed postoperatively at 1, 4, and 7 days and 1, 3, 6, and 12 months. RESULTS: Overall pain scores were higher in the Proclear group at 1 day (P = .000) and 4 days (P = .027). The N&D group had an increase in corneal infiltrates at 4 days (P = .025) and 1 week (P = .017). At 1 month, 40.4% of patients in the Proclear group and 18.6% in the N&D group had a 1 or more line decrease in best spectacle-corrected visual acuity (BSCVA) (P = .002). Although there was a trend toward a higher haze rate in the Proclear group, it was not statistically significant (P = .064). There was no statistically significant difference in uncorrected visual acuity, goal of emmetropia, contrast sensitivity, or reepithelialization. CONCLUSIONS: The N&D lens produced less pain and better postoperative results in terms of haze and BSCVA at 1 month. However, it led to a higher incidence of corneal infiltrates. There was no difference between the lenses in the end result at 12 months.