Effect of timolol on refractive outcomes in eyes with myopic regression after laser in situ keratomileusis: a prospective randomized clinical trial

Role of corneal epithelial thickness during myopic regression in femtosecond laser-assisted in situ keratomileusis and transepithelial photorefractive keratectomy

BACKGROUND

The study aimed to investigate the relationship between changes in corneal epithelial thickness and the outcome of myopic regression after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and transepithelial photorefractive keratectomy (TPRK).

METHODS

This study included 45 eyes of 25 patients undergoing FS-LASIK and 44 eyes of 24 patients undergoing TPRK. Myopic regression occurred in these patients postoperatively from 8 to 21 months. The corneal epithelial thickness was measured using a spectral-domain optical coherence tomography at the onset of regression, 3 months after treatment, and 3 months after drug withdrawal.

RESULTS

Compared with that of preoperation, corneal epithelial thickness increased when regression occurred in both groups (all P < 0.05). The thickness of central corneal epithelium in FS-LASIK and TPRK groups reached 65.02 ± 4.12 µm and 61.63 ± 2.91 µm, respectively. The corneal epithelial thickness decreased when myopic regression subsided after 3 months of steroid treatment compared to the onset (P < 0.05). With a decrease in corneal epithelial thickness, the curvature of the anterior corneal surface, central corneal thickness, and refractive power all decreased (all P < 0.05). The corneal epithelial thickness and refractive error remained relatively stable after 3 months of treatment withdrawal (P > 0.05).

CONCLUSION

The corneal epithelial thickness determined the outcome of myopic regression similarly in FS-LASIK and TPRK. When the corneal epithelium thickened, regression occurred. After steroid treatment, epithelial thickness decreased whereas regression subsided.

Effect of timolol maleate (0.5%) in the management of myopic regression post laser-assisted in-situ keratomileusis: Clinical and topographical outcomes

Purpose

The aim of this study was to analyze the effect of timolol maleate (0.5%) eye drops in the treatment of myopic regression after laser-assisted in-situ keratomileusis (LASIK).

Methods

The study was conducted at a tertiary care eye hospital in north India between April 2017 & March 2018 as a prospective interventional study. Patients who underwent uneventful myopic LASIK with hansatome mechanical keratome and presented with regression were included in the study. Baseline demographic characteristics, time to presentation with regression best-corrected visual acuity (BCVA), refraction, intraocular pressure, central corneal thickness and keratometry were recorded at baseline and at each follow-up visit. The enrolled patients were prescribed timolol maleate (0.5%) eyedrops twice daily. They were followed up every month till 3 months on timolol maleate (0.5%) eyedrops and at 6 months post stopping the treatment.

Results

Twenty-nine eyes of 15 patients were enrolled in the study. Mean pre LASIK spherical equivalent (SE) was - 7.48 ± 2.9 Diopters (Range-3.125 to -11.75 Diopters) and mean regression spherical equivalent was -1.02 ± 1.1 Diopters. There was a decrease in mean SE from presentation (intervention start point) up to 6 months follow-up (-1.34 ± 0.89 to -0.30 ± 0.29 Diopters). While posterior corneal curvature (K1 and K2 Back) changed significantly over treatment period (P = 0.0029, P = 0.0024 respectively), changes in anterior corneal curvature (K1 and K2 Front) were not significant (P = 0.05, P = 0.06 respectively). Central corneal thickness (CCT) and intraocular pressure (IOP) did not change significantly over treatment course.

Conclusion

Timolol maleate (0.5%) eyedrop is an effective modality for the treatment of refractive regression post LASIK circumventing the need for laser re-treatment in such patients. The most probable mechanism is reversal of the anterior bowing of the cornea in response to intraocular pressure changes.

Reduction of corneal epithelial thickness during medical treatment for myopic regression following FS-LASIK

Background

To evaluate corneal epithelial thickness change during medical treatment for eyes with myopic regression after femtosecond laser-assisted in situ keratomileusis (FS-LASIK).

Methods

This study included 84 eyes of 54 subjects diagnosed with myopic regression after FS-LASIK and treated using topical steroid and anti-glaucoma drugs. Corneal epithelial thickness was measured using Fourier-domain optical coherence tomography before and after treatment. Subjects were divided into three groups based on their corneal epithelial thickness at the time of myopic regression and regression analyses were used to investigate the association between corneal epithelial thickness, visual acuity, and refraction. Logistic regression and receiver operating characteristic (ROC) curve analysis was performed to determine whether corneal epithelial thickness could predict the success of treatment, improvements of ≥ two lines in uncorrected distance visual acuity and ≥ 0.5 diopter in refraction or K.

Results

Corneal epithelial thickness decreased with greater change in the center as myopic regression subsided during medical treatment. Subgroup with the thickest epithelium (≥ 62 μm) showed a higher success rate and greater changes in refraction and vision. Reduced magnitude of corneal epithelial thickness showed significant correlations with changes of K and refractive error (all P < 0.001). Corneal epithelial thickness was a significant factor for the success of treatment and ROC curve showed that corneal epithelial thickness > 60.50 μm had 81.5% sensitivity and 84.2% specificity for the success of medical treatment.

Conclusion

Corneal epithelial thickness decreases proportionally with the magnitude of improvement of myopic regression during treatment with steroid and anti-glaucoma drugs in post-LASIK eyes with myopic regression.

Review of Laser Vision Correction (LASIK, PRK and SMILE) with Simultaneous Accelerated Corneal Crosslinking - Long-term Results

Purpose: Laser in-situ keratomileusis (LASIK), photorefractive keratectomy (PRK) and small-incision lenticule extraction (SMILE) are safe and effective refractive surgical procedures. However, complications include regression of treatment and iatrogenic keratectasia which can be severe and sight-threatening. In order to reduce these complications, simultaneous corneal cross-linking (CXL) is currently being added to these refractive procedures. This review analyses current long-term literature (≥ 1 year follow-up) on refractive surgery and simultaneous CXL (LASIK Xtra, PRK Xtra and SMILE Xtra) to determine its overall safety and efficacy.Methods: A comprehensive literature search of various electronic databases (PubMed, PubMed Central and MEDLINE) was performed up to 9^th February 2019. Efficacy and safety indices are calculated where possible.Results: Ten relevant studies were found for LASIK Xtra, 4 for PRK Xtra and 1 for SMILE Xtra. The total number of eyes included in this review was 1,189: 347 eyes for LASIK Xtra, 300 eyes for LASIK-only, 298 for PRK Xtra, 204 for PRK-only, 40 for SMILE Xtra and none for SMILE-only. Current studies show that refractive surgery and simultaneous CXL produces comparable or better results in terms of refractive and keratometric stability than refractive surgery alone. However, case reports of complications such as corneal ectasia, diffuse lamellar keratitis and central toxic keratopathy have also recently been published.Conclusions: Simultaneous accelerated CXL and refractive surgery is effective for the treatment of myopia. However, it is as yet unclear if the additional CXL step reduces the incidence of iatrogenic keratectasia. Further long-term comparative studies would be useful in evaluating safety and efficacy of this procedure. More research should also be performed to titrate the UV-A irradiation settings for an optimal outcome.

Refractive regression after laser in situ keratomileusis

Uncorrected refractive errors are a leading cause of visual impairment across the world. In today's society, laser in situ keratomileusis (LASIK) has become the most commonly performed surgical procedure to correct refractive errors. However, regression of the initially achieved refractive correction has been a widely observed phenomenon following LASIK since its inception more than two decades ago. Despite technological advances in laser refractive surgery and various proposed management strategies, post-LASIK regression is still frequently observed and has significant implications for the long-term visual performance and quality of life of patients. This review explores the mechanism of refractive regression after both myopic and hyperopic LASIK, predisposing risk factors and its clinical course. In addition, current preventative strategies and therapies are also reviewed.

Combined application of prophylactic corneal cross-linking and laser in-situ keratomileusis - a review of literature

Laser in-situ keratomileusis (LASIK) is safe and effective laser refractive procedures in treating refractive errors. However, regression of treatment and iatrogenic keratectasia remain to be a major concern, especially in treating thin cornea with high ametropia. Collagen cross-linking (CXL) is an effective method in stopping keratoconus progression through increasing the biomechanical strength of the cornea. Adjuvant cross-linking to refractive procedures can theoretically help prevent regression and reduce the risk of keratectasia development by increasing the mechanical stability of cornea. During the procedure, riboflavin is directly applied to the corneal stroma, thereby reducing the need of de-epithelialization as in the conventional protocol for keratoconus. Currently, there is still no consensus regarding the indication of CXL during refractive procedure, nor any standardized treatment protocol. This article aims to summarize the current evidence regarding the use of adjuvant CXL in LASIK.

Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia

Purpose

To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia.

Methods

We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (−3.00 to −12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events.

Results

The safety and efficacy indices were 0.82 ± 0.29 and 0.67 ± 0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of −0.74 ± 0.99 D occurred from 3 months to 12 years after LASIK (p < 0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient, r = −0.28, p = 0.02), but not with the changes in central corneal thickness (r = −0.08, p = 0.63). No vision-threatening complications occurred in any case.

Conclusions

Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening.

Efficacy and Safety of Topical Timolol Eye Drops in the Treatment of Myopic Regression after Laser In Situ Keratomileusis: A Systematic Review and Meta-Analysis

Aims. The aim of this study was to assess the efficacy and safety of timolol in the treatment of myopic regression after laser in situ keratomileusis (LASIK). Methods. We searched MEDLINE, CENTRAL, EMBASE, China National Knowledge Infrastructure (CNKI), and Chinese Biological Medicine (CBM) from the inception to July 2015 for relevant randomized controlled trials that examined timolol therapy for myopic regression. The methodological quality of the studies included was assessed using the Revman 5.3 software. Results. We included six clinical trials involving 483 eyes in this review, including 246 eyes in treated group and 237 eyes in controlled group. We observed statistically significant improvements on the postoperative SE in the 3 months. However, the change of CCT was not statistically different between the control group and the experimental group. There were fewer cases of IOP, UDVA, and CDVA in treated group having significant difference from the controlled group. Conclusions. Topical timolol could be an effective treatment for reduction of myopic regression especially the spherical errors after myopic LASIK. Further RCTs with larger sample sizes for these trials are warranted to determine the efficacy and limitation for myopic regression after LASIK.

Effect of orthokeratology in patients with myopic regression after refractive surgery

PURPOSE

To evaluate the clinical effect of orthokeratology (ortho-K) lenses and to introduce the fitting steps of ortho-K lens for myopic regression after keratorefractive surgery.

METHODS

Twenty-one eyes from 12 patients with myopic regression after keratorefractive surgery were fitted with ortho-K lenses and followed up for 12.11±3.68 months. The mean K value of the peripheral cornea was used to speculate preoperative central corneal K value, estimated K. After dispensing the lenses according to estimated K, biomicroscopic examination including fluorescein staining and over-refraction were performed to determine the final K and final lens power.

RESULTS

LogMAR uncorrected visual acuity was 0.48±0.39 before and 0.00±0.00 after wearing ortho-K lenses (p<0.001). Pre-fitted refractive error was -1.87±1.05 diopters (D) in myopia, 0.54±0.42 D in astigmatism, and spherical equivalent of -2.14±1.01 D. At the final visit myopia level and spherical equivalent significantly decreased to -0.73±0.84 D (p<0.001) and -1.01±0.87 D (p<0.001), respectively. Estimated K was 8.07±0.36 mm, and final K used for ortho-K prescription was 8.19±0.30 mm. Final K significantly correlated with K value of pre-fitted peripheral cornea (r=0.737, p<0.001) and estimated K (r=0.721, p<0.001), respectively. There was no correlation between pre-fitted degree of myopia and the Final lens power (r=0.429, p=0.053).

CONCLUSIONS

Ortho-K lenses may be an effective solution for patients with myopic regression following keratorefractive surgery. Estimated K value can be used as reference value in ortho-K prescription.