Corneal Haze Grade Research Articles

Haze prevention following photorefractive keratectomy in brown eyes

To study corneal haze following myopic photorefractive keratectomy (PRK) in a high-risk population and to assess methods for minimizing the risk. The medical records of 150 patients who underwent PRK were reviewed. A total of 300 eyes were included. All patients underwent myopic PRK using the Allegretto Wave Concerto 500Hz (Wavelight AG, Erlangen, Germany)excimer laser platform with intraoperative mitomycin-C (MMC) application. Demographic data including age, gender and ethnicity in addition to preoperative and postoperative subjective manifest refraction, spherical equivalent, best-corrected distance visual acuity, uncorrected distance visual acuity (UDVA), postoperative corneal haze grade and other possible postoperative complications were retrieved. Hanna grading (0-4+) was used to evaluate corneal haze. The patients were comprised of 74 men (49.3%) and 76 women (50.7%). The mean age at the time of surgery was 26.5±6.0 (range, 17-46) years. All patients were Saudis with brown irides. UDVA improved to 20/25 in 93.8% at 3 months. The mean and standard deviation of preoperative spherical equivalent was -3.02±1.63 (range, -7.63 - -0.13). At 3 months, postoperative spherical equivalent improved to 0.05±0.50 (-1.00 - +1.00). At 6 months, 13.6% exhibited corneal haze of grade 1, and none exhibited grades 2 or 3. The results of this study confirmed that patients with brown irides can achieve favorable outcomes after PRK. MMC, postoperative topical steroids and ultraviolet protection evidently play a major role in preventing corneal haze in high-risk populations.

Haze and Visual Acuity Loss After Sequential Photorefractive Keratectomy and Corneal Cross-linking for Keratoconus.

To investigate the results after photorefractive keratectomy (PRK) followed immediately by standard 30-minute corneal cross-linking (CXL) for keratoconus. This retrospective study included 26 eyes of 16 patients with keratoconus. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (SE) and cylinder, apical keratometry, corneal higher order aberrations (HOAs), and corneal haze were evaluated. Mean follow-up was 32 ± 8 months (range: 19 to 50 months) and mean patient age was 31 ± 5 years (range: 24 to 40 years). Mean UDVA improved significantly from 0.80 ± 0.39 to 0.32 ± 0.36 logMAR after surgery (P < .001), but the mean CDVA worsened significantly from 0.07 ± 0.09 to 0.15 ± 0.14 logMAR after surgery (P = .006). Thirteen eyes (50%) lost at least one line of CDVA, 3 eyes (12%) lost two lines, and 4 eyes (15%) lost three lines. SE, cylinder, and apical keratometry decreased significantly. Corneal haze grade 1 was found in 15 eyes (57.7%), grade 2 in 6 eyes (23.1%), and grade 3 in 1 eye (3.8%). A significant correlation was seen between postoperative CDVA loss and corneal haze (P = .001) and history of atopy (P < .01), but not with corneal HOA change. Despite an improvement in UDVA and topographic values, the loss of CDVA, explained by postoperative haze, demonstrates that this procedure should be approached with caution, may not be as safe as initially thought, especially in patients with atopy and can cause severe visual acuity loss. [J Refract Surg. 2019;35(2):109-114.].

Laser‐assisted subepithelial keratectomy versus epipolis laser in situ keratomileusis for myopia: a meta‐analysis of clinical outcomes

To identify possible differences between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis for myopia. Meta-analysis. Patients from previously reported comparative studies treated by laser-assisted subepithelial keratectomy versus epipolis laser in situ keratomileusis. A systematic literature retrieval was conducted in the MEDLINE, EMBASE and Cochrane Library, up to January 2013. The included studies were subject to a meta-analysis using a RevMan 5.1 version software. The differences in efficacy, predictability, safety, epithelial healing time, pain perception and corneal haze formation. A total of six studies involving 517 eyes were included. There were no statistically significant differences in the final proportion of eyes with uncorrected visual acuity of 6/6 or better (P = 0.43), mean postoperative uncorrected visual acuity (P = 0.53), final proportion of eyes with refraction within ± 0.50 D (P = 0.62) and ± 1.00 D (P = 0.16) of target, final proportion of eyes losing two or more lines of best spectacle-corrected visual acuity (P = 1.00), healing time of corneal epithelium (P = 0.58), final proportion of eyes with corneal haze grade 0.5 or higher (P = 0.26), and corneal haze levels (P = 0.36). There were no significant differences in efficacy, predictability, safety, epithelial healing time and corneal haze formation between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis, but the result was limited. Future more data are required to detect the potential differences between the two procedures.

Clinical Effectiveness of Topical Cyclosporine A 0.05% After Laser Epithelial Keratomileusis

To evaluate the effect of topical cyclosporine A 0.05% after laser epithelial keratomileusis (LASEK). This retrospective nonrandomized comparative analysis was performed in 40 patients (80 eyes) with myopia who underwent flap-off LASEK. Twenty patients (group A) were treated with topical cyclosporine A 0.05% in combination with conventional treatment, and 20 patients (group B) received conventional treatment only. In each group, 10 patients had preoperative dry eye. Uncorrected visual acuity, refractive error, corneal haze grade, symptom score, and ocular surface parameters were measured in both groups before LASEK and at 1, 2, 4, and 8 weeks postoperatively. There were no significant differences between the groups in postoperative uncorrected visual acuity, spherical equivalent, corneal haze grade, Schirmer test values, and keratoepitheliopathy scores. Group A had lower symptom scores (0.80 ± 0.52 vs.1.35 ± 0.49; P < 0.01) and higher tear film break-up time (BUT) (8.05 ± 1.39 vs. 6.55 ± 1.39 seconds; P < 0.01) compared with group B at 4 weeks after LASEK. In addition, in preoperative dry eye patients, symptom scores and tear film BUT returned to preoperative level at 4 weeks postoperatively in group A, whereas they returned to preoperative level at 8 weeks in group B. Treatment with topical cyclosporine A 0.05% can improve ocular discomfort and increase tear film BUT during the early postoperative period, especially in patients with preoperative dry eye.

Refractive Lenticule Re-Implantation after Myopic ReLEx: A Feasibility Study of Stromal Restoration after Refractive Surgery in a Rabbit Model

To investigate the potential of refractive lenticule (RL) storage and re-implantation in vivo as a method for reversing RL extraction (ReLEx) and restoring corneal stromal volume. ReLEx [-6.00 diopter (D) correction] was performed on six New Zealand White rabbits in one eye. Each extracted RL was tagged and orientated before storage at -80°C for 28 days. Each RL was then re-implanted autologously in the correct orientation after flap relifting. All animals were monitored for 28 days before being euthanized for immunohistochemical analysis. Unoperated fellow eyes were used as controls. All animals had regular pre- and postoperative slit lamp photography, in vivo confocal microscopy, anterior segment optical coherence tomography (AS-OCT), keratometry, and topography. No intra-operative complications occurred and RL re-implantation was performed without complication. A mild intrastromal haziness was noted on day 3 after re-implantation (corneal haze grade: 2.20 ± 0.45), but corneas were clear on day 28 (0.20 ± 0.27). RL re-implantation restored central corneal thickness, and keratometric and topographic indices to near pre-operative values. Wound healing processes, marked by fibronectin and tenascin, and a few inflammatory cells were present along the re-implanted lenticular interfaces. No myofibroblasts formation, and Ki67- and TUNEL-positive cells were observed in the corneal stroma on postoperative day 28. RL storage and re-implantation is a feasible technique for restoring stromal volume after myopic ReLEx, and may provide a method for restoring tissue in ectatic corneas, or provide an opportunity for further refractive surgery and presbyopic treatment.

Mechanical Superficial Keratectomy for Corneal Haze After Photorefractive Keratectomy With Mitomycin C and Extended Wear Contact Lens

To evaluate the clinical results of a mechanical keratectomy with mitomycin C (MMC) and extended wear contact lens (EWCL) for the treatment of corneal haze after photorefractive keratectomy (PRK) of high myopia. Eye Research Center, Khatam-al-Anbia Eye Hospital, Mashhad University of Medical Sciences, Iran. : In a retrospective interventional case series, we enrolled 15 eyes of 9 patients who previously underwent PRK for high myopia and developed corneal haze and regression. Mechanical removal of corneal haze was done by using a surgical blade number 15. Then, MMC (0.02%) was used for 2 minutes. An EWCL was applied for 1 month. The main outcome measures were uncorrected visual acuity, best-corrected visual acuity, spherical equivalent (SE), and corneal haze grade. All patients were followed for a minimum of 6 months. The mean age of the patients was 25.66 ± 7.03 years; 7 patients were men and 2 patients were women. The mean best-corrected visual acuity before superficial keratectomy was 20/80 (range, 20/200-20/50) and improved to 20/20 after treatment (P < 0.05). Thirteen eyes (86.6%) achieved an uncorrected visual acuity of at least 20/40. The mean preoperative SE was 3.91 ± 1.30, and the mean final postoperative SE was -0.85 ± 1.19 (P < 0.05). Eight eyes (53%) were within 1 diopter of emmetropia. Corneal haze in all patients declined to a trace haze or complete clearness. No recurrence occurred during the mean follow-up time of 12 months. Superficial keratectomy with MMC and EWCLs is effective in reducing persistent and refractory corneal haze after PRK.

Management of Corneal Ectasia After LASIK with Combined, Same-Day, Topography-Guided Partial Transepithelial PRK and Collagen Cross-Linking: The Athens Protocol

To evaluate a series of patients with corneal ectasia after LASIK that underwent the Athens Protocol: combined topography-guided photorefractive keratectomy (PRK) to reduce or eliminate induced myopia and astigmatism followed by sequential, same-day ultraviolet A (UVA) corneal collagen cross-linking (CXL). Thirty-two consecutive corneal ectasia cases underwent transepithelial PRK (WaveLight ALLEGRETTO) immediately followed by CXL (3 mW/cm(2)) for 30 minutes using 0.1% topical riboflavin sodium phosphate. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, keratometry, central ultrasonic pachymetry, corneal tomography (Oculus Pentacam), and endothelial cell counts were analyzed. Mean follow-up was 27 months (range: 6 to 59 months). Twenty-seven of 32 eyes had an improvement in UDVA and CDVA of 20/45 or better (2.25 logMAR) at last follow-up. Four eyes showed some topographic improvement but no improvement in CDVA. One of the treated eyes required a subsequent penetrating keratoplasty. Corneal haze grade 2 was present in 2 eyes. Combined, same-day, topography-guided PRK and CXL appeared to offer tomographic stability, even after long-term follow-up. Only 2 of 32 eyes had corneal ectasia progression after the intervention. Seventeen of 32 eyes appeared to have improvement in UDVA and CDVA with follow-up >1.5 years. This technique may offer an alternative in the management of iatrogenic corneal ectasia.

Apical nodular subepithelial corneal scar after retreatment in hyperopic photorefractive keratectomy

PurposeTo report a complication, apical nodular subepithelial corneal scar, that can occur after hyperopic photorefractive keratectomy (PRK) retreatment. SettingIstanbul University Eye Research Center, Istanbul, Turkey. MethodsTwelve eyes of 6 patients with apical nodular subepithelial corneal scar were retrospectively studied. Mean age of the 5 men and 1 woman was 30.2 years ± 5.4 (SD). All eyes had hyperopic PRK retreatment for regression 9.5 ± 1.44 months after primary hyperopic PRK. Mean spherical equivalent refraction of the residual hyperopia before retreatment was +4.67 ± 0.81 diopters (D). All patients had a corneal haze grade of less than 1+. Hyperopic PRK retreatment was performed with a 193 nm excimer laser (Chiron Technolas Keracor 116). ResultsApical nodular subepithelial corneal scars developed within the first month of hyperopic PRK retreatment and progressed until the third month in 12 eyes of 6 patients. The lesion was round and symmetrical in both eyes, smaller than 2.0 mm, and centrally located. During the mean 40.66 ± 2.46 month follow-up, the lesion did not change in size or density. Mean spherical equivalent refraction after retreatment was 2.88 ± 0.88 D (range +1.50 to +4.00 D) at 1 month and +4.36 ± 1.83 D at last follow-up. Refraction was unmeasurable in 3 eyes. Five eyes lost 1 line of best spectacle-corrected visual acuity and 7 eyes, 2 or more lines. The surface regularity indexes were higher than 2.00 in all the eyes. ConclusionHyperopic PRK retreatment may cause the sight-threatening complication of apical nodular subepithelial corneal scar. This complication behaves unlike corneal haze and does not resolve spontaneously over time.

Excimer laser photorefractive keratectomy resulting more myopia postoperatively than preoperatively

SUMMARY Purpose: To present three patients who experienced excessive myopic regression which resulted in more myopia after excimer laser surgery. Methods: All patients, white males, 31 to 35 years old, were treated with the VISX 20/20 excimer laser. Results: Patient 1 had a manifest refraction of -5.00 diopters before PRK and 9 months later it was -4.25 +0.50 x 65o. Six months after retreatment it was -6.00 diopters and the patient had a corneal haze grade 3. Patient 2 had a manifest refraction of -12.25 +2.25 x 10o before surgery and -14.25 +1.00x 105o after wards with a corneal haze grade 3. Patient 3 had a manifest refraction of -5.75 +0.25 x 25o and four months after surgery it was -6.25 with a corneal haze grade 2. Conclusion: The corneal healing process after excimer is notwell understood and patients should be informed about the remote possibility that their myopia may increase after PRK and that they may develop a significanthaze.