A comparison of different depth ablations in the treatment of painful bullous keratopathy with phototherapeutic keratectomy

Exploring single-cell RNA sequencing as a decision-making tool in the clinical management of Fuchs' endothelial corneal dystrophy

Single-cell RNA sequencing (scRNA-seq) has enabled the identification of novel gene signatures and cell heterogeneity in numerous tissues and diseases. Here we review the use of this technology for Fuchs' Endothelial Corneal Dystrophy (FECD). FECD is the most common indication for corneal endothelial transplantation worldwide. FECD is challenging to manage because it is genetically heterogenous, can be autosomal dominant or sporadic, and progress at different rates. Single-cell RNA sequencing has enabled the discovery of several FECD subtypes, each with associated gene signatures, and cell heterogeneity. Current FECD treatments are mainly surgical, with various Rho kinase (ROCK) inhibitors used to promote endothelial cell metabolism and proliferation following surgery. A range of emerging therapies for FECD including cell therapies, gene therapies, tissue engineered scaffolds, and pharmaceuticals are in preclinical and clinical trials. Unlike conventional disease management methods based on clinical presentations and family history, targeting FECD using scRNA-seq based precision-medicine has the potential to pinpoint the disease subtypes, mechanisms, stages, severities, and help clinicians in making the best decision for surgeries and the applications of therapeutics. In this review, we first discuss the feasibility and potential of using scRNA-seq in clinical diagnostics for FECD, highlight advances from the latest clinical treatments and emerging therapies for FECD, integrate scRNA-seq results and clinical notes from our FECD patients and discuss the potential of applying alternative therapies to manage these cases clinically.

Late-Onset Chronic Corneal Fistula Following Phototherapeutic Keratectomy: A Case Report and Importance of Early Detection

BACKGROUND We report a case of late-onset chronic fistula in a decompensated cornea after multiple ocular surgeries and a recent phototherapeutic keratectomy (PTK). CASE REPORT A 73-year-old woman presented to our service with a past ocular history of bilateral chronic angle closure glaucoma and pseudophakic bullous keratopathy in the left eye. Given a history of long-term uncontrolled glaucoma with advanced disc cupping and poor visual potential, the patient underwent multiple palliative procedures, including, most recently, a PTK. Few years later she presented with a spontaneous late onset of slowly appearing corneal leak on fluorescein staining upon routine clinical examination. Corrected distance visual acuity was hand motion and intraocular pressure (IOP) was 40 mmHg in the affected eye. Serial anterior segment optical coherence tomography (AS-OCT) sections were obtained, which aided in understanding the current presentation and revealed distinctive multilayer corneal changes during the healing process. The patient was successfully managed with cyanoacrylate corneal gluing and ocular hypotensive medications, which halted the corneal leak. CONCLUSIONS We report a case of a rare finding of corneal fistula in an eye with multiple previous ocular surgeries, and provide an explanation of the possible etiopathogenesis. We also highlight the pivotal role of AS-OCT for evaluating such cases and stress the importance of early detection of similar subtle leaks in the setting of a formed anterior chamber, which can often be missed, carrying a risk of infection.

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.

Use of Bowman's membrane electrocautery in blind eyes with painful bullous keratopathy not amenable to corneal transplantation: a retrospective case series

PURPOSE

This study evaluated the safety and efficacy of Bowman's membrane electrocautery in blind painful eyes with bullous keratopathy not amenable to corneal transplantation.

METHODS

Eleven eyes of 11 subjects with painful bullous keratopathy and poor visual potential who underwent electrocautery of Bowman's membrane at a tertiary referral ophthalmology clinic were reviewed retrospectively. Subject demographics and preoperative and postoperative data were collected, including description of pain, slit lamp biomicroscopy, best corrected visual acuity, topical medication use, and complications. Efficacy of the procedure on pain reduction, bullae resolution, and topical medication use were assessed at post-operative visits. Safety was also evaluated based on any complications.

RESULTS

Bowman's membrane electrocautery effectively resolved bullae in all eyes examined up to 6 months postoperatively; however, 2 eyes had recurrence by 1 year. Mean age at the time of surgery was 69.8 years and mean duration of follow-up was 15.4 months. Pain reduction was achieved in all eyes at 1 month, but 1 subject had pain recurrence by 6 months and another by 1 year. The median number of drops per day decreased from 6 preoperatively to 1.7 at 6 months. Two subjects who had underlying advanced ophthalmic disease had a mild reduction in vision.

CONCLUSION

Bowman's membrane electrocautery is a safe and minimally invasive procedure for the management of painful bullous keratopathy in eyes with low vision potential and not amenable to corneal transplantation. Duration of effect appears to last at least 6 months and up to 3 years post-procedure.

Burr-Assisted Peripheral Superficial Keratectomy for the Treatment of Persistent Symptomatic Peripheral Corneal Edema

PURPOSE

To describe a simple technique of diamond burr-assisted superficial keratectomy for the treatment of peripheral corneal edema.

CASES PRESENTATION

Two patients with persistent symptomatic peripheral corneal edema underwent superficial keratectomy with the use of a diamond ophthalmic burr. The efficacy of the treatment was evaluated clinically as well as with anterior segment optical coherence tomography. During the postoperative follow-up period, no adverse events were observed and corneal edema reduced significantly. The patients were asymptomatic, no epithelial cysts could be identified clinically, and visual acuity remained unchanged.

CONCLUSION

Peripheral superficial keratectomy could be an effective alternative for the treatment of peripheral, symptomatic corneal edema.

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.

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.

Corneal endothelial cell dysfunction: etiologies and management

A transparent cornea is essential for the formation of a clear image on the retina. The human cornea is arranged into well-organized layers, and each layer plays a significant role in maintaining the transparency and viability of the tissue. The endothelium has both barrier and pump functions, which are important for the maintenance of corneal clarity. Many etiologies, including Fuchs’ endothelial corneal dystrophy, surgical trauma, and congenital hereditary endothelial dystrophy, lead to endothelial cell dysfunction. The main treatment for corneal decompensation is replacement of the abnormal corneal layers with normal donor tissue. Nowadays, the trend is to perform selective endothelial keratoplasty, including Descemet stripping automated endothelial keratoplasty and Descemet’s membrane endothelial keratoplasty, to manage corneal endothelial dysfunction. This selective approach has several advantages over penetrating keratoplasty, including rapid recovery of visual acuity, less likelihood of graft rejection, and better patient satisfaction. However, the global limitation in the supply of donor corneas is becoming an increasing challenge, necessitating alternatives to reduce this demand. Consequently, in vitro expansion of human corneal endothelial cells is evolving as a sustainable choice. This method is intended to prepare corneal endothelial cells in vitro that can be transferred to the eye. Herein, we describe the etiologies and manifestations of human corneal endothelial cell dysfunction. We also summarize the available options for as well as recent developments in the management of corneal endothelial dysfunction.

Superficial Keratectomy and Conjunctival Advancement Hood Flap (SKCAHF) for the Management of Bullous Keratopathy: Validation in Dogs With Spontaneous Disease

PURPOSE

To evaluate the efficacy of superficial keratectomy and conjunctival advancement hood flap (SKCAHF) for the treatment of bullous keratopathy in canine patients.

METHODS

Nine dogs (12 eyes) diagnosed with progressive corneal edema underwent superficial keratectomy followed by placement of conjunctival advancement hood flaps. The canine patients were examined pre- and postoperatively using in vivo confocal microscopy, ultrasonic pachymetry (USP), and Fourier-domain optical coherence tomography (FD-OCT). All owners responded to a survey regarding treatment outcomes.

RESULTS

Mean central corneal thickness (CCT) as measured by FD-OCT was 1163 ± 290 μm preoperatively and significantly decreased postoperatively to 795 ± 197 μm (P = 0.001), 869 ± 190 μm (P = 0.005), and 969 ± 162 μm (P = 0.033) at median postoperative evaluations occurring at 2.2, 6.8, and 12.3 months, respectively. Owners reported significant improvement (P < 0.05) in vision and corneal cloudiness at 6.8 and 12.3 months postoperatively. The percentage of cornea covered by the conjunctival flap was correlated (P = 0.0159) with a reduction in CCT by USP at 12.3 months postoperatively. All canine patients were comfortable pre- and postoperatively.

CONCLUSIONS

SKCAHF results in a reduction of corneal thickness in canine patients with bullous keratopathy. The increase in corneal thickness over time, after performing SKCAHF, is likely because of progressive endothelial decompensation. This surgery is a potentially effective intervention for progressive corneal edema in dogs that may have value in treatment of human patients with bullous keratopathy.

Pseudophakic bullous keratopathy

Pseudophakic bullous keratopathy is characterized by corneal stromal edema with epithelial and subepithelial bullae due to cell loss and endothelial decompensation through trauma during cataract surgery. Patients present decreased vision, tearing, and pain caused by ruptured epithelial bullae. Cataract affects approximately 20 million people worldwide, and this complication can occur in 1 to 2% of the cataract surgeries. This study reviewed the bullous keratopathy etiopathogenesis and the clinical and surgical treatment available for this corneal disease.

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.

Long-term symptomatic relief of bullous keratopathy with amniotic membrane transplant

The purpose of this study was to assess the long-term outcome of patients with symptomatic bullous keratopathy after amniotic membrane transplant. A retrospective cohort study includes that 20 patients with symptomatic bullous keratopathy, who have underwent amniotic membrane transplant at the Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital & Alice Ho Miu Ling Hospital, Hong Kong between 04/1998 and 06/2011, were invited back. Clinical examination was performed, including, pain score assessment (pain score out of 10), epithelial healing, and vision. A total of 21 eyes of 20 patients returned for our study. The majority of eyes experienced pain reduction (94 %), with a significant mean pain score difference of 6.8 ± 2.6, 2-tail p < 0.001 (99 % CI 4.9-8.7). The mean pre-operative and post-operative pain scores were 7.3 ± 2.9 and 0.5 ± 1.0, respectively. 16 eyes (76 %) were completely pain free, and 10 eyes (47 %) remained symptom free after a mean follow-up of 39.0 ± 36.3 months (range 5-171 months). The median epithelial healing time was 2 weeks (range 1-20 weeks). Amniotic membrane transplant may be considered as a longer-term treatment for bullous keratopathy patients, especially in patients with poorer visual prognosis, but it may also be used as an interim measure for patients awaiting corneal transplant.

Alternatives to corneal transplantation for the management of bullous keratopathy

PURPOSE OF REVIEW

Corneal transplantation remains the gold-standard treatment for bullous keratopathy patients as it provides symptomatic relief and visual rehabilitation. As corneas are not always available for transplant, alternative treatments have to be considered for alleviation of discomfort and pain.

RECENT FINDINGS

Various treatment options available in such cases include conjunctival flaps, anterior stromal puncture, amniotic membrane transplantation, phototherapeutic keratectomy, bandage contact lenses, and hypertonic saline eye drops. A combination of the above treatments can be employed depending upon the severity of bullous keratopathy and co-existing corneal edema. New potential treatments include collagen cross-linking (CXL), cultured endothelial cell injection, and topical treatment with Rho-associated kinase (ROCK) inhibitor.

SUMMARY

There is a lack of clinical trials comparing the safety and efficacy of the currently available treatment options for the management of bullous keratopathy. The effect of these treatments on subsequent corneal transplant has not been observed. CXL seems to offer short-term benefit for relief of pain. Newer potential treatment modalities such as ROCK inhibitors are claimed to be useful for the reversal of early edema associated with corneal endothelial dysfunction; however, long-term clinical trials are awaited.

Autologous tragal perichondrium transplantation: a novel approach for the management of painful bullous keratopathy

PURPOSE

To introduce autologous tragal perichondrium transplantation as a novel surgical modality for the management of intractable symptomatic bullous keratopathy.

METHODS

In three eyes of three patients with painful bullous keratopathy, autologous tragal perichondria were transplanted on the corneal surface with the human amniotic membrane transplanted above. We included an additional three eyes of three patients with painful bullous keratopathy who received amniotic membrane transplantation only to serve as controls. Clinical symptom outcomes were assessed using a visual analogue scale at postsurgical months 1, 3, 5, 7, and 9. In addition, transplanted tragal perichondrium and amniotic membrane complex tissue button obtained from one patient who underwent penetrating keratoplasty was evaluated by immunohistochemical analysis of CD34, vimentin, and alcian blue staining.

RESULTS

All three patients who underwent autologous tragal perichondrium and human amniotic membrane co-transplantation showed improvements in pain and tearing. However, all three patients in the control group experienced aggravation of tearing and no further improvement of pain 3 months after surgery. In addition, one patient in the control group developed premature degradation of the amniotic membrane. Histopathologic and immunohistochemical analysis showed intact surface epithelization and positive CD34, vimentin and alcian blue staining of transplanted tragal perichondria.

CONCLUSIONS

The tragal perichondrium has a high mechanical structural force and high potency due to well-organized epithelization and the presence of mesenchymal stem cells. Autologous tragal perichondrium transplantation may be an effective modality for the management of painful bullous keratopathy.

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.

Prospective comparison of two suturing techniques of amniotic membrane transplantation for symptomatic bullous keratopathy

PURPOSE

To determine the outcomes of a modified amniotic membrane transplantation (AMT) suturing technique for pain and discomfort relief in patients with symptomatic bullous keratopathy (BK).

DESIGN

Randomized, double-blind controlled clinical trial.

METHODS

setting: Ankara Research and Training Hospital 1st and 2nd Eye Clinics, Ankara, Turkey. study population: This prospective study included 39 eyes (39 patients) with BK presenting with intractable pain or discomfort and poor visual potential. intervention: Patients were randomly assigned into two groups: in group 1 (21 patients), patients underwent a modified AMT suturing technique; a groove was prepared by vacuum trephine on the recipient cornea and the edges of the punch-shaped amniotic membrane (AM) were sutured to this groove with the basement membrane side up. In group 2 (18 patients), patients underwent the standard AMT suturing to the cornea. main outcome measure: During a mean follow-up of 27.3 +/- 8.5 months (standard deviation) (range, 12 to 36 months), epithelial healing, persistence of AM, pain relief, and visual changes were analyzed and were compared between groups.

RESULTS

The mean age (P = .15), the mean follow-up (P = .73), and the mean preoperative visual acuity (P = .53) were similar in both groups. With the modified suturing technique, the postoperative visual acuity was better (P = .03), epithelialization time was shorter (P < .001), and the AM remained longer (P < .001). Successful epithelialization was achieved in 20 eyes (95.3%) in group 1, and in 16 eyes (88.9%) in group 2 (P = .586). The pain scores of patients in group 1 remained stable (P = .223) over time, however increased from the first week to the third month postoperatively in group 2 (P = .046).

CONCLUSIONS

The modified AMT suturing technique has a similar epithelialization rate to standard AMT suturing to cornea. Though technically more demanding, shorter epithelialization time, longer persistence of AM, and stable pain scores in the postoperative period makes this a promising method for the treatment of symptomatic BK.

Indications and outcomes of phototherapeutic keratectomy in the developing world

PURPOSE

To analyze the indications and outcomes of phototherapeutic keratectomy (PTK) in the developing world.

METHODS

In this retrospective study, the records of 203 consecutive eyes of 191 patients who had undergone PTK at a tertiary eye care center were evaluated. The parameters assessed were indications of PTK, demographic features, best spectacle-corrected visual acuity (BSCVA), and pachymetry. PTK was done by using a 193-nm Ar-F Excimer laser (Chiron Technolas Keracor 217 C) in a 6-mm optic zone. Patients were followed up for 6 months.

RESULTS

The most common indication of PTK was symptomatic bullous keratopathy (103 eyes). The patients were divided into 2 groups: those with bullous keratopathy (PTK BK) and those with superficial corneal pathologies (PTK CS). In the PTK CS group, the most common indications were Salzmann nodular degeneration (n = 27) and spheroidal degeneration (n = 22). BSCVA improved from 20/222 (0.09) to 20/86 (0.23) in the PTK CS group and 20/384 (0.05) to 20/202 (0.09) in the PTK BK group (P < 0.0001 in both groups). There was a significant decrease in the number of patients with severe symptoms in the PTK-BK (P < 0.0001) and PTK-CS (P = 0.017) groups. The change in BSCVA was significantly related to both pre-PTK BSCVA and pachymetry in PTK-BK.

CONCLUSIONS

PTK is an efficacious treatment modality for symptomatic relief and visual gain in cases with superficial corneal involvement and bullous keratopathy.

Amniotic membrane transplantation for painful bullous keratopathy

PURPOSE

To establish the effectiveness of amniotic membrane transplantation (AMT) in relieving pain and discomfort in patients with painful bullous keratopathy and its role in improving vision in eyes with visual potential.

METHODS

Seven eyes of seven consecutive patients with painful corneal conditions were included in a retrospective interventional noncomparative case series performed at Maidstone General hospital, Maidstone, UK. Amniotic membrane transplantation was performed in seven eyes. Pain relief, epithelial healing, and visual changes were evaluated. Pain relief and freedom from discomfort were considered for the success of the surgery.

RESULTS

The mean follow-up was 26.57 weeks (range 11 to 53 weeks). Pain relief was achieved in all seven (100%) eyes. Associated symptoms including foreign body sensation, photophobia, and tearing subsided significantly in all patients starting soon after the first postoperative day. Vision improved in 5 (71.42%) patients.

CONCLUSIONS

AMT is an effective alternative for the management of patients with painful bullous eratopathy. Besides pain relief and reduction of ocular inflammation it remains unclear whether this procedure can also be used to improve vision in eyes with visual potential.

Pseudophakic corneal edema: A review of mechanisms and treatments

PURPOSE

To review the pathological mechanisms and treatments for pseudophakic corneal edema (PCE), one of the most common indications for penetrating keratoplasty.

METHODS

The literature was examined for the molecular biology associated with PCE and for the surgical and medical treatments for this disorder.

RESULTS

The incidence of PCE has recently been decreasing because of improved surgical instrumentation, including improvements in intraocular lens designs that cause less trauma to the corneal endothelium. Extracellular matrix and growth factor abnormalities occur in PCE corneas and recently, the role of aquaporins, which are involved in the regulation of fluid movement across cells, has been investigated.

CONCLUSIONS

Although newer treatment options have been suggested, penetrating keratoplasty still remains the most definitive treatment and has the highest success rate.

Amniotic membrane transplantation for bullous keratopathy in eyes with poor visual potential

PURPOSE

To evaluate the long-term outcomes of epithelial debridement and amniotic membrane transplantation (AMT) for pain and discomfort relief in patients with symptomatic bullous keratopathy and poor visual potential.

SETTING

Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA.

METHODS

This retrospective study included 18 eyes (18 patients) with bullous keratopathy presenting with intractable pain or discomfort and poor visual potential. After epithelial debridement, all eyes had AMT with the basement membrane side up. During a mean follow-up of 25.1 months +/- 9.6 (SD) (range 12 to 45 months), pain relief, epithelial healing, and visual changes were analyzed.

RESULTS

Pain relief was obtained in 88% of patients. Sixty-six percent of eyes had complete resolution of ocular discomfort starting soon after the first postoperative day. One eye had evisceration for persistent pain 10 months postoperatively. Corneal epithelial healing was complete in all except 1 eye. Remaining complaints included foreign-body sensation (5%), tearing (11%), and photophobia (5%).

CONCLUSIONS

Amniotic membrane transplantation was a safe, effective, and long-lasting treatment modality for intractable pain associated with chronic bullous keratopathy in eyes with poor visual potential. It can be an alternative to conjunctival flaps for the long-term management of patients with bullous keratopathy in whom corneal transplantation is not indicated. A comparison of the efficacy of AMT with that of other surgical procedures must be performed.

Phototherapeutic keratectomy: 12 years of experience

BACKGROUND

Phototherapeutic keratectomy (PTK) has been employed as a surgical tool to treat corneal disease for more than 10 years. The laser has made it possible to remove superficial corneal opacities and thereby restore vision. The 193 nm ultraviolet light separates molecules and splits molecules in biological tissue, thereby ablating it. About 0.25 microm of tissue is ablated by each pulse. The development of the excimer laser technique has been fast. It has principally focused on refractive surgery but has also benefited PTK.

CORNEAL DYSTROPHIES

The ability to delay or postpone corneal grafting in superficial corneal dystrophies represents a very important achievement. Map-dot-fingerprint dystrophy or basal membrane dystrophy is a common indication for PTK. Other dystrophies such as Meesman's, Reis-Bückler's, Thiel-Benke's, granular, macular, lattice and Schnyder's can be treated, although with differing degrees of success and varying rates of recurrence. Subepithelial scarring in Fuchs' dystrophy has been ablated. Other trials have involved the removal of substantial parts of the stroma in order to reduce the load on the endothelium. Recurrent dystrophic changes can likewise be removed from corneal grafts and thus prevent the need for regrafting.

RECURRENT EROSIONS

Laser treatment has made it possible to manage wound-healing problems better after recurrent erosions. Recurrent erosions are the most common indications for PTK: several studies show good and persistent effects with this type of treatment. Persistent epithelial defects of various origins, among them corneal ulcers resulting from allergic disease, can likewise be treated.

SCAR TISSUE

Scars after surgery such as pterygeum excision can be removed. Smooth muscle actin containing fibroblasts in old scars should be given special consideration in PTK. Excimer laser surgery can be successfully combined with conventional surgery to remove excessive scar tissue, Salzmann's nodules and very flaky and coarse band keratopathy. Irregular corneal surfaces following ulcers and injuries pose problems that have so far proved difficult to overcome. Thinning is often seen after bacterial corneal ulcers or after herpes simplex keratitis. A rough or uneven surface can be made smoother by using modulators during treatment by casting a new surface under a hard contact lens (PALM technique), a surface that is then projected into the stroma by laser ablation. Modern techniques linking the excimer laser with computerized corneal topography and wavefront analysis promise to further improve the smoothing capacities of lasers and to increase the quality of optical results.

COMPLICATIONS

The most feared complication of PTK is the postoperative infection. These are rare. Haze is usually not prominent but scar tissue formation of a more persistent type has been noted after laser surgery in eyes with pre-existing surgical scars. Keratectasia has been described after PTK. Failure due to deep opacities or a surface that is too uneven is a more common frustration. This paper reviews advances in excimer laser treatment of corneal disease.