Indications and outcomes of phototherapeutic keratectomy in the developing world

Long-Term Outcomes of Phototherapeutic Keratectomy for Bullous Keratopathy

PURPOSE

To report the long-term outcomes after phototherapeutic keratectomy (PTK) for the treatment of bullous keratopathy.

METHODS

This is a retrospective medical record review of all patients with symptomatic bullous keratopathy who underwent PTK between June 2005 and March 2019 at the Royal Victorian Eye and Ear Hospital who were followed up for at least 12 months after the procedure. Medical records were used to extract demographic data, etiology of bullous keratopathy, complication rates, and subsequent procedures after PTK. The main outcomes recorded were pain and recurrence of bullae, which were assessed according to three time periods: 0 to 3 months, 4 to 12 months, and greater than 12 months after PTK.

RESULTS

During the study period, 64 eyes of 64 patients underwent PTK for bullous keratopathy. The mean follow-up duration was 51 months (range 12-140). The most common indication was pseudophakic bullous keratopathy (44% of cases). Pain had resolved in 88% of eyes within 0 to 3 months, 77% of eyes between 3 and 12 months (P = 0.031, compared with 0-3 months), and 70% of eyes with greater than 12-month follow-up (P = 0.131, compared with 3-12 months). Bullae recurred in 17% of eyes within 0 to 3 months, 22% of eyes between 3 and 12 months (P < 0.001 compared with 0-3 months), and 33% of eyes after the 12-month follow-up (P < 0.001 compared with 3-12 months). Eighty-six percent of patients undergoing PTK had no postoperative complications, and 73% of cases did not require subsequent procedures.

CONCLUSIONS

PTK is effective in providing long-term symptom relief from bullous keratopathy in most of the treated patients.

Phototherapeutic keratectomy: Indications, methods and decision making

Phototherapeutic keratectomy (PTK) involves treating anterior corneal lesions by superficial corneal ablation using an excimer laser (193 nm). Some of the commonly treated conditions include recurrent corneal erosions (RCE), corneal dystrophies, spheroidal degeneration, keratoconus, and corneal scars. We discuss various techniques of PTK including large area PTK, focal PTK, and multifocal PTK and alternatives to PTK. Masking agents like hyaluronate, methylcellulose, and dextran are recommended to help achieve a better outcome when ablating irregular corneal surfaces. Antifibrotic agents like mitomycin C reduce the chances of recurrence of the disease, apart from minimizing the postoperative scarring. Some of the complications include induced hyperopia and irregular astigmatism, haze, recurrence, and corneal thinning. However, earlier postoperative recovery, possibility of a repeat procedure, and ability to control the depth of ablation make PTK a promising, minimally invasive alternative to keratoplasty in cases with anterior corneal pathologies.

Transepithelial Surface Ablation With Mitomycin C for the Treatment of Chronic Central Corneal Scars Following Adenoviral Keratoconjunctivitis

PURPOSE

To assess visual and refractive outcomes and recurrence rates of subepithelial infiltrates after corneal surface ablation with mitomycin C (MMC) 0.02% for the treatment of chronic corneal scars following epidemic keratoconjunctivitis and to compare these results with a control group receiving only medical treatment.

METHODS

This was a retrospective case series enrolling patients with central corneal scars following epidemic keratoconjunctivitis. Patients were divided into two groups: (1) control with clinical follow-up and refractive correction with glasses or rigid gas-permeable contact lenses when necessary and (2) transepithelial phototherapeutic keratectomy (PTK) with MMC 0.02%, combined with photorefractive keratectomy (PRK) in selected cases (treatment group). Signs and symptoms, corrected distance visual acuity (CDVA) in logMAR units, manifest and cycloplegic refraction, and depth of the corneal opacities were assessed.

RESULTS

Thirty-five eyes of 27 patients (11 men [40.7%] and 16 women [59.3%]) were enrolled, with a mean follow-up of 54.4 ± 19.7 and 27.5 ± 22.8 months in the control and treatment groups, respectively. Mean improvement in CDVA was 0.13 ± 0.17 logMAR (P = .007) in the control group and 0.29 ± 0.24 logMAR (P = .001) in the treatment group. Intergroup comparison showed a greater improvement in the treatment group (P = .041). Mean hyperopic shift induced in the treatment group was +0.46 ± 1.20 diopters. The recurrence rate of subepithelial infiltrates was 77.7% in the control group and 11.7% in the treatment group throughout the follow-up (54.4 ± 19.7 and 27.5 ± 22.8 months, respectively).

CONCLUSIONS

Corneal surface ablation with MMC 0.02% was efficient in treating corneal scars following adenoviral epidemic keratoconjunctivitis, with greater visual improvement in comparison to clinical treatment and a decreased rate of infiltrate recurrence. [J Refract Surg. 2020;36(1):55-61.].

Fourier-domain optical coherence tomography-guided phototherapeutic keratectomy for the treatment of anterior corneal scarring

AIM

To evaluate the safety, visual and anatomic outcomes of fourier-domain optical coherence tomography (FD-OCT)-guided excimer laser phototherapeutic keratectomy (PTK) combined with photorefractive keratectomy (PRK) surgery in treating anterior corneal scarring.

METHODS

Clinical data of 23 eyes of 21 patients with anterior corneal scarring underwent FD-OCT-guided PTK and PRK from Dec. 2014 to Jul. 2016 were reviewed. Patients were assessed for preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity (CS), FD-OCT, corneal topography and colour figures of anterior segments.

RESULTS

The preoperative corneal pathologic conditions included viral keratitis (7 patients, 7 eyes), band keratopathy (2 patients, 4 eyes), corneal dystrophy (4 patients, 4 eyes), traumatic corneal disease (2 patients, 2 eyes) and corneal chemical injury (6 patients, 6 eyes). Mean follow-up time was 10.65 (range, 3-19)mo. UCVA (in logMAR) improved from a mean of 0.79 (95%CI, 0.28-1.29) preoperatively to a mean of 0.45 (95%CI, 0.29-0.62) postoperatively (P=0.021). BSCVA (in logMAR) improved from 0.57 (95%CI, 0.27-0.88) preoperatively to a mean of 0.28 (95%CI, 0.15-0.41) postoperatively (P=0.001). Corneal topographic indices postoperatively showed significant improvement in corneal cylinder (P=0.009), the surface regularity index (P=0.007) and surface asymmetry index (P=0.00). Postoperative spherical equivalent averaged -0.53 diopters (-1.49 to 0.42). No complications were associated with the treatment.

CONCLUSION

FD-OCT-guided PTK combined with PRK is safe and effective for the treatment of anterior corneal scarring by eliminating or reducing corneal opacities.

Salzmann nodular degeneration: prevalence, impact, and management strategies

Purpose

This review will summarize the clinical and histological presentation of Salzmann nodular degeneration (SND), its prevalence and risk factors, potential underlying mechanisms, diagnostic tools, management options, and impact on cataract surgery and co-morbid ocular surface diseases.

Method

PubMed review of 44 articles published between 1976 and 2018.

Results

SND is a corneal disease characterized by whitish gray or bluish nodules on the peripheral or central cornea. The clinical presentation of SND is variable and the nodules can be asymptomatic or cause foreign body sensation and/or blurred vision. Histologically, SND appears as subepithelial nodules with thin overlying epithelium, disrupted or absent Bowman’s layer, and activated fibroblasts within the nodule. SND pathogenesis is not fully understood but is thought to involve poor epithelial protection and disruption of the epithelial–stromal interface, allowing for penetration of epithelially derived growth factors into the stroma and subsequent activation of stromal fibroblasts, eventually leading to sub-epithelial deposition of disorganized extracellular membrane components. SND most commonly occurs in Caucasian females in a bimodal distribution, occurring in the fifth or eighth and ninth decades of life. Risk factors for SND include ocular surface diseases and surgery. Surgical intervention is recommended in individuals with symptomatic nodules – primarily superficial keratectomy performed with or without intraoperative mitomycin C, photokeratectomy, and/or amniotic membrane transplantation. These procedures have been successful in removing the lesion and reducing corneal irregularity, but have variable recurrence rates (0–31%).

Conclusion

The pathogenesis of SND is complex and multifactorial. Advances in diagnostic and treatment modalities have allowed for earlier and more accurate diagnosis and effective treatment of SND.

Phototherapeutic keratectomy

Phototherapeutic keratectomy is an excimer laser-based surgical procedure widely performed by corneal surgeons for treating anterior corneal stromal pathologies. Phototherapeutic keratectomy helps by ablating the corneal stroma, thereby improving corneal clarity and smoothening the surface. Transient discomfort and induced hyperopia from corneal flattening are the immediate postoperative concerns. The long-term course is often marked by the recurrence of original corneal pathology and corneal haze formation. Phototherapeutic keratectomy, however, allows for repeat stromal ablation for managing recurrences, as the corneal thickness permits, without affecting the outcome of future keratoplasty. Adjunctive methods such as topical mitomycin-C may be additionally used to reduce recurrence rates. Also, various masking agents such as carboxymethyl cellulose, sodium hyaluronate, and dextran are used in eyes with irregular corneal surface to allow for uniform stromal ablation. Overall, phototherapeutic keratectomy has provided corneal surgeons an additional surgical tool, particularly those residing in developing nations where the availability of donor corneal tissue is an important limiting factor.

Recurrent rates and risk factors associated with recurrent painful bullous keratopathy after primary phototherapeutic keratectomy

OBJECTIVE

To assess the recurrent rate, mean survival time, and risk factors associated with recurrent painful bullous keratopathy (BK) after primary treatment with phototherapeutic keratectomy.

METHODS

Medical records from 72 patients (72 eyes) who had phototherapeutic keratectomy for painful BK were evaluated. Data for sex, age, duration of BK, associated ocular and systemic diseases (hypertension, diabetes mellitus, ischemic heart disease, asthma, dyslipidemia, and rheumatoid arthritis), frequency and degree of pain (grade 1-3), visual acuity, corneal thickness, intraocular pressure, and laser setting were extracted and analyzed.

RESULTS

The mean age of the patients was 64.2±11.4 years. The mean preoperative duration of BK was 15.0±11.0 months. Most patients had pseudophakic BK (69.40%). Majority of the cases had grade 3 degree of pain (48.60%). Glaucoma and hypertension were markedly found among these patients (51.40% and 19.40%, respectively). Preoperative mean intraocular pressure and corneal thickness were 13.70±4.95 mmHg and 734.1±83.80 µm, respectively. The mean laser diameter and depth were 8.36±1.22 mm and 38.89±8.81 µm, respectively. Systemic disease was significantly associated with the risk for developing recurrent painful BK (P=0.022, hazard ratio [HR] 1.673, 95% confidence interval [CI] 1.08-2.58). The overall recurrent rate was 51%. The average duration time of recurrent painful BK was 17.3±12.9 months (range 1-50 months). The median survival time before recurrence was 29.0±6.6 months.

CONCLUSION

Systemic disease was found to be the only risk factor significantly associated with the development of recurrent painful BK. Low recurrent rate and long mean survival time showed that phototherapeutic keratectomy was effective in relieving recurrent painful BK and can be used as an alternative procedure for patients waiting for corneal transplantation.

Clinical outcomes of phototherapeutic keratectomy in eyes with Thiel-Behnke corneal dystrophy

PURPOSE

To investigate the functional and morphologic midterm outcome of phototherapeutic keratectomy (PTK) for Thiel-Behnke corneal dystrophy diagnosed by gene-mutation analysis.

DESIGN

Retrospective, single-center clinical study.

METHODS

Between July 2001 and May 2010, 10 consecutive PTKs were performed in 10 eyes of 5 patients (2 male, 3 female; mean age: 55 ± 13 years) with superficially accentuated opacities caused by Thiel-Behnke corneal dystrophy and were followed up for at least 12 months (range: 12-108 months). Main outcome measures included (1) best-corrected visual acuity (BCVA), (2) uncorrected visual acuity (UCVA), (3) spherical equivalent, and (4) recurrence rate. The probability of recurrence of Thiel-Behnke corneal dystrophy after PTK was calculated using the Kaplan-Meier method for survival analysis.

RESULTS

The p.Arg555Gln mutation was found within the TGFBI gene in all 5 patients. Average logarithm of minimal angle of resolution (logMAR) BCVA change was -0.55 ± 0.26. Average logarithm UCVA change was -0.54 ± 0.31. In 5 of the 10 eyes, recurrence of central superficial opacification was clinically identified during the follow-up periods, and in 4 of those 5 eyes, the level of the recurrence was so significant that the visual acuity was reduced more than 2 lines. The maximum follow-up period of the 1 eye without significant post-PTK recurrence was 108 months.

CONCLUSIONS

PTK is a successful therapy for Thiel-Behnke corneal dystrophy, and results in midterm stable visual acuity and corneal transparency. Unlike in Reis-Bücklers corneal dystrophy cases, PTK delays the need for more invasive surgical intervention in Thiel-Behnke corneal dystrophy.

Phototherapeutic keratectomy

Phototherapeutic keratectomy (PTK) is done regularly for anterior corneal diseases such as corneal dystrophies, corneal degenerations, scars, and band-shaped keratopathy. The various indications include both therapeutic and visual. The aim of this article is to discuss the therapeutic indications for PTK, the specific technique pertaining to a specific etiology, the various other procedures like amniotic membrane graft combined with PTK or PTK being done for recurrences in the grafts, and PTK done before cataract surgery when the anterior corneal pathology coexists with the cataract. Post PTK management such as healing of an epithelial defect, use of steroids in the post PTK period, recurrences of primary disease pathology, and infections, will be discussed. Methods of literature search: A Medline search was carried out for articles in the English language, with the keywords, phototherapeutic keratectomy, band-shaped keratopathy, spheroidal degeneration, scars, bullous keratopathy, and corneal dystrophy. The relevant references are mentioned here.

Excimer laser phototherapeutic keratectomy for the treatment of silicone oil-induced band-shaped keratopathy

PURPOSE

To study the efficacy of excimer laser phototherapeutic keratectomy (PTK) for the treatment of band-shaped keratopathy (BSK).

METHODS

A retrospective analysis of case records of 20 eyes of 20 patients with silicone oil-induced BSK and significant media haze that underwent PTK was conducted. Improvement in corneal clarity and best-corrected visual acuity (BCVA) was assessed at 6 weeks postoperatively.

RESULTS

The mean ablation depth was 62.63±23.82 μm (range 25 to 100 μm). Postoperative course was uneventful, and the mean time for healing of the epithelial defect was 4.25±2.43 days. All the eyes showed significant improvement in corneal clarity at 6 weeks postoperatively. The mean score of corneal clarity increased from 1.15±0.74 preoperatively to 3.35±0.49 at 6 weeks postoperatively (P<0.001). At postoperative 6 weeks, 90% (18 eyes) showed an improvement in BCVA of 2 or more lines, whereas the BCVA remained unchanged in two eyes (10%). There was a hyperopic shift postoperatively with a mean shift of spherical equivalent of 2.23±2.08 D. At the end of the last follow-up (mean: 16.75±4.2 months; range 11-24 months), two eyes with silicone oil in the vitreous chamber and with inferior peripheral and shallow retinal detachment showed recurrence of BSK for which retreatment with PTK was given.

CONCLUSIONS

Phototherapeutic keratectomy is an effective option for the treatment of silicone oil-induced BSK with significant improvement in corneal clarity. However, the gain in visual acuity depends on the coincident posterior segment pathologic condition. Further, in eyes with retained silicone oil, there is a risk of recurrence of BSK for which retreatment may be required.

Phototherapeutic keratectomy outcomes in superficial corneal opacities

Purpose

Compare the effectiveness of Phototherapeutic keratectomy (PTK) in treatment corneal dystrophies versus superficial corneal scars: visual outcomes, recurrence rate and safety profile.

Methods

PTK was performed in 51 eyes of 51 patients. Data regarding the indications for PTK, ablation depth, symptomatic relief, pre-and postoperative best spectacle-corrected visual acuity (BSCVA), spherical equivalent changes, recurrence and complications were analyzed. The indications for PTK in our study were classified into two categories – group A: patients with corneal dystrophies (n = 23) and the other group B (n = 28) with other indications.

Results

The average age of the patients was 47 years (±16.4). The mean follow up period was 15.16 months (±10.01 months). Post operatively, there were no significant complications. While the overall BSCVA in the patients improved from 20/41 (0.484) to 20/32 (0.645), group A showed improvement from 20/35 (0.561) to 20/29 (0.687), as compared to group B in which BSCVA improved from 20/47 (0.421) to 20/33 (0.611). The most common indication in group A was granular corneal dystrophy (n = 10) and the most common indication in group B was post traumatic/infectious corneal scar or opacity (n = 10). Eighty-six percent (n = 44) of all patients had alleviation of symptoms. Recurrence of symptoms was seen in 3 eyes of recurrent corneal erosions which required retreatment.

Conclusion

PTK is a safe and effective procedure. The outcome of this study suggests that PTK improves BSCVA. PTK appears to improve ocular surface health. Furthermore, PTK can be recommended to most patients with corneal dystrophies as a treatment modality prior to other more invasive procedure (viz. penetrating keratoplasty).

Phototherapeutic keratectomy for the treatment of corneal opacities after epidemic keratoconjunctivitis

PURPOSE

To assess visual results and compare methods of measuring central corneal thickness (CCT) and corneal opacity thickness (COT) in patients with corneal opacities induced by epidemic keratoconjunctivitis (EKC) and treated with phototherapeutic keratectomy (PTK) using low-dose mitomycin C (MMC).

DESIGN

Prospective consecutive case series.

METHODS

Patients with chronic adenoviral corneal opacity underwent transepithelial PTK with MMC 0.002% for 1 minute. The presence of photophobia, the best spectacle-corrected visual acuity (BSCVA), and the contrast sensitivity were evaluated. CCT measurements were obtained with ultrasound pachymeter (US), ultrasound biomicroscopy (UBM), Scheimpflug tomography (Pentacam Oculus), and optical coherence tomography (OCT Visante). COT measurements were obtained with UBM, Pentacam, and OCT.

RESULTS

Thirty-one eyes of 23 patients, comprising 15 women (65.2%) and 8 men (34.8%), mean age 41.8 years, were enrolled in the study. Duration of visual disturbance was 19.1 ± 14 months. The number of patients with photophobia was reduced from 100% to 29% after surgery. BSCVA improved 2 or more lines in 78% of the patients at 12 months. A hyperopic shift of 1.52 ± 0.91 diopters was achieved. Contrast sensitivity improved in both photopic and mesopic conditions. For each of the instruments, the CCT postoperative mean was significantly smaller than the preoperative measurement (P < .0001) and COT values were significantly reduced in comparison to the preoperative values (P < .001).

CONCLUSION

Improvements in photophobia, BSCVA, and contrast sensitivity were observed in patients treated using excimer laser PTK with low-dose MMC for subepithelial infiltrates.

Update on phototherapeutic keratectomy

PURPOSE OF REVIEW

To review all recent publications on the use of phototherapeutic keratectomy (PTK).

RECENT FINDINGS

Recent studies confirm the beneficial outcomes of PTK in a variety of anterior corneal disorder: anterior stromal scars, dystrophies of the corneal epithelium and the anterior stroma, and elevated corneal lesions. They also try to evaluate the biomechanical properties of eyes with granular corneal dystrophy undergoing PTK, in an effort to prevent iatrogenic ectasia. The different genotypes in patients with transforming growth factor, beta-induced linked corneal dystrophies have recently been correlated to the surgical outcome after PTK. An extensive review of recurrent corneal erosion syndrome identified PTK as the most effective treatment. In the developing world, the most common indication for PTK is still bullous keratopathy, as PTK can be successfully used while waiting for penetrating keratoplasty.

SUMMARY

PTK can successfully treat a variety of conditions of the anterior cornea. New studies may further expand its use.