Ocular surface changes after excimer laser phototherapeutic keratectomy

Combined Topography-Guided Trans-Epithelial PRK and PTK for Treatment of Calcific Band Keratopathy Unresponsive to EDTA Chelation Therapy

Purpose

To report a case of Calcific Band Keratopathy (CBK) treated successfully with transepithelial Phototherapeutic keratectomy (PTK) combined with customized Photorefractive Keratectomy (PRK).

Methods

One case report.

Results

A 63-year-old man presented to our clinic with decreased visual acuity and ocular discomfort in both eyes. Clinical examination revealed a horizontal gray-whitish band across the central cornea in both eyes, supporting the diagnosis of CBK. Initially, an EDTA chelating procedure was attempted, but it had no effect on the deeper calcium deposits and on the irregular corneal morphology. In both eyes, a topography-guided trans-epithelial PRK with PTK was performed. Following PRK surface ablation, PTK was used to smooth the ablated area using 1% hydroxymethylcellulose as masking agent. The procedure was completed applying 0.02% Mitomycin C. At the 1-month follow-up, both eyes corneal opacities were resolved, and the LE visual acuity had improved to 20/63 and the RE to 20/20, which was maintained at the 3-, 6-, and 12-months follow-up. Furthermore, there was an improvement in spherical equivalent and corneal morphological irregularity index.

Conclusion

CBK may be successfully treated using a combined topography-guided trans-epithelial PRK and PTK.

Modified Transepithelial Phototherapeutic Keratectomy for Band Keratopathy

Objectives: To report the outcomes of novel modified transepithelial phototherapeutic keratectomy (PTK) in treating band keratopathy (BK). Methods: A retrospective analysis was performed on patients who underwent PTK for BK at the Sussex Eye Laser Clinic, Nuffield Health, Brighton. Patients with BK obscuring the visual axis, affecting visual acuity, or causing discomfort were considered for PTK. All the patients underwent preoperative evaluation, including preoperative corneal topography and optical coherence tomography. Modified transepithelial PTK was performed without using EDTA for chelation or alcohol for epithelium debridement. Patients were followed up for one week and then every two weeks after that until two months. Preoperative and postoperative best corrected visual acuities (BCVA) were compared using a paired t-test. Results: We studied 15 eyes of nine patients undergoing novel PTK for BK. The mean age was 80 ± 5.73 years. The mean pre-treatment visual acuity was 0.68 ± 0.17 logMAR (range: 0.6 logMAR to 1 logMAR) and improved to 0.22 ± 0.09 logMAR (p < 0.05), ranging from 0.18 to 0.48 logMAR at two months following PTK. None of the patients complained of ocular discomfort following the procedure. A repeat procedure was not required for any of these patients. Conclusions: Modified transepithelial PTK is an effective procedure for improving visual outcomes in patients with band keratopathy and should be considered for the treatment of band keratopathy.

The effect of EDTA solution on corneal endothelial cells in rabbits

Corneal disease threatens vision globally. Among corneal diseases, calcific band keratopathy has severe effects on vision owing to its unique location. Currently, ethylene diamine tetraacetic acid (EDTA) chelation remains the most important treatment. However, only the safety of low-dose topical EDTA eye drops is well established in humans. Therefore, the purpose of this study was to determine the safe dose range of EDTA for calcific band keratopathy surgery and its toxic effects on rabbit eyes. Rabbits were administered different doses of EDTA solutions (0.50, 0.20, 0.10, 0.05, and 0.01 M) for twenty minutes. In day seven, the rabbits were euthanized and pathological examination was performed for cornea. We found severe corneal edema in 0.50 M group, while milder edema in lower-concentration treated groups. Followed by corneal thickness measurement, the measured values increase to the peak in post-operative three day (0.20 M group) or one day (lower-concentration groups), then decreased. Groups comparison shown significant difference between BSS control group and higher concentration groups (0.20 M and 0.10 M) (P < 0.001) in observation period, but no significance was observed between low concentration and control group in the day seven after surgery (P > 0.05). Confocal microscopy examination suggested, the number of corneal endothelial cells significantly decreased from 3428.6 ± 180.3 cells/mm² to 2808 ± 80.6 cells/mm² in the 0.50 M group, while the lower-concentration groups showed lesser toxic effects on corneal endothelial cells. Finally, our histological examination demonstrated inflammation in each experimental group and dose-dependent, compared with control group. Our study found 0.05 M and 0.01 M EDTA solutions had no obvious toxic effect on the corneal endothelium compared with higher concentration. However, further study of EDTA side effect by clinical trials, and therapeutic effect observation with different concentration are necessary.

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.].

Clinical and genetic aspects of the TGFBI-associated corneal dystrophies

Corneal dystrophies are a group of inherited disorders localized to various layers of the cornea that affect corneal transparency and visual acuity. The deposition of insoluble protein materials in the form of extracellular deposits or intracellular cysts is pathognomic. Mutations in TGFBI are responsible for superficial and stromal corneal dystrophies. The gene product, transforming growth factor β induced protein (TGFBIp) accumulates as insoluble deposits in various forms. The severity, clinicopathogenic variations, age of the onset, and location of the deposits depend on the type of amino acid alterations in the protein. Until 2006, 38 different pathogenic mutants were reported for the TGFBI-associated corneal dystrophies. This number has increased to 63 mutants, reported in more than 30 countries. There is no effective treatment to prevent, halt, or reverse the deposition of TGFBIp. This review presents a complete mutation update, classification of phenotypes, comprehensive reported incidents of various mutations, and current treatment options and their shortcomings. Future research directions and possible approaches to inhibiting disease progression are discussed.

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.

Goblet cells of the normal human bulbar conjunctiva and their assessment by impression cytology sampling

Goblet cells of the conjunctiva are the main source of mucus for the ocular surface. The objectives of this review are to consider the goblet cells as assessed by various histological, cytological and electron microscopy methods, and to assess the consistency of published reports (over more than 25 years) of goblet cell density (GCD) from impression cytology specimens from nominally healthy human subjects. Reported GCD values have been notably variable, with a range from 24 to 2226 cells/mm² for average values. Data analysis suggests that a high density of goblet cells should be expected for the healthy human conjunctiva, with a tendency toward higher values in samples taken from normally covered locations (inferior and superior bulbar conjunctiva) of the open eye (at 973 +/- 789 cells/ mm²) than in samples taken from exposed (interpalpebral) locations (at 427 +/- 376 cells/mm²). No obvious change in GCD was found with respect to age, perhaps because the variability of the data did not allow detection of any age-related decline in GCD. Analyses of published data from 33 other sources indicated a trend for GCD to be lower than normal across a spectrum of ocular surface diseases.

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.

Impression cytologic analysis after corneal collagen cross-linking using riboflavin and ultraviolet-A light in the treatment of keratoconus

PURPOSE

To report impression cytologic (IC) results after corneal cross-linking (CXL) using riboflavin and ultraviolet-A light in the treatment of keratoconus and compare the data with those from a group of subjects with the same disease.

METHODS

Forty eyes were distributed into 2 groups: patients in group 1 underwent CXL, whereas patients in group 2 received riboflavin 0.1% eyedrops for 1 month of topical use. IC specimens were obtained from all eyes before treatment and 1 and 3 months after treatment.

RESULTS

Patients in group 1 showed a decrease in goblet cell density on the superior conjunctiva after CXL (P = 0.008) but no difference on the temporal conjunctiva or in the cornea. Patients in group 2 demonstrated improvement in cell-to-cell contact of epithelial cells and reduced keratinization on the temporal conjunctiva after treatment (P = 0.003 and P = 0.034, respectively) but no changes on the superior conjunctiva or in the cornea. Fisher exact test comparison of IC total scores after treatment revealed no difference between groups.

CONCLUSIONS

Despite changes in goblet cell density after corneal CXL in the superior conjunctiva and an improvement in the morphology of epithelial cells after the use of riboflavin eyedrops, comparison of total IC scores showed no difference between groups.

Successful treatment of superficial corneal irregularity by lamellar keratectomy using the femtosecond laser

The authors report successful vision restoration after cataract surgery using a femtosecond laser in a patient with superficial corneal irregularity. A 62-year-old man with corneal irregularity and a cataract in the left eye was referred for treatment. The superficial corneal opacity causing the irregularity was mainly located within the superficial anterior cornea. To acquire a stable keratometric value, which is important for accurate calculation of intraocular lens power, lamellar keratectomy using a femtosecond laser (IntraLase; AMO, Irvine, CA) was performed to smooth the cornea surface. Postoperatively, corneal smoothness was restored and a stable keratometric value was acquired. Vision was improved with the expected refraction after cataract surgery. The femtosecond laser may be an effective surgical tool for patients with superficial corneal irregularity and cataracts.

Combined ethylenediaminetetraacetic acid chelation, phototherapeutic keratectomy and amniotic membrane transplantation for treatment of band keratopathy

PURPOSE

The objective of this study is to evaluate the therapeutic efficacy of ethylenediaminetetraacetic acid (EDTA) chelation and excimer laser phototherapeutic keratectomy (PTK) combined with amniotic membrane transplantation (AMT) for the treatment of band keratopathy (BK).

METHODS

Eleven eyes in ten patients with BK received combined PTK (ablation zone of central 7.0-7.5 mm, depth of 50 microm), EDTA chelation (0.05 M, 3 minutes), and amniotic membrane transplantation using fibrin glue. Preand postoperative best corrected visual acuities, symptom changes, reepithelialization time, cosmesis, recurrence, and complications were analyzed.

RESULTS

Visual acuity improved in three eyes (27.3%) and did not change in eight eyes (72.7%). Symptoms improved in all patients, and the mean reepithelialization time was 10.6+/-5.3 days. The cosmetic results were good in eight eyes (72.7%) and were fair in three eyes (27.3%). During the mean follow-up period of 11.4+/-6.1 months (range, 6 to 23 months), no postoperative complications or recurrences were observed.

CONCLUSIONS

The combination of EDTA chelation, PTK, and AMT is safe and effective for the treatment of band keratopathy.

Excimer laser exacerbation of Avellino corneal dystrophy

We review the clinical, histopathological, and ultrastructural findings and DNA phenotyping of a patient with Avellino corneal dystrophy exacerbated by laser in situ keratomileusis. The findings are reported and interpreted in the context of a literature review. The case highlights the possible difficulty of recognizing subtle dystrophic findings, as well as the importance of avoiding refractive surgical intervention in patients with Avellino corneal dystrophy to avoid exacerbation of dystrophic deposits in the cornea and subsequent reduction in vision.

Multistage approach to uveitic cataract management in children

Phototherapeutic keratectomy, cataract extraction and hydrophobic acrylic lens implantation, Nd:YAG laser capsulotomy, glaucoma valve implantation, and intravitreal steroid injections resulted in substantial visual improvement in three eyes of two children with complicated cataract due to severe uveitis. At follow-up of 6 months to 4 years, the children had clear corneas and normal intraocular pressures.

Impression cytology of the ocular surface

Impression cytology refers to the application of a cellulose acetate filter to the ocular surface to remove the superficial layers of the ocular surface epithelium. These cells can then be subjected to histological, immunohistological, or molecular analysis. Proper technique is essential as the number of cells sampled can vary considerably. Generally two to three layers of cells are removed in one application but deeper cells can be accessed by repeat application over the same site. Applications for impression cytology include diagnosing a wide range of ocular surface disorders, documenting sequential changes in the conjunctival and corneal surface over time, staging conjunctival squamous metaplasia, and monitoring effects of treatment. It is also a useful investigational tool for analysing ocular surface disease with immunostaining and DNA analysis. It is non-invasive, relatively easy to perform, and yields reliable information about the area sampled with minimal discomfort to the patient. Major ophthalmic centres should develop and introduce this technique into routine clinical practice. This is best achieved with a team approach including the ophthalmologist, pathologist, microbiologist, and the immunologist.

Roughness of Excimer Laser Ablated Corneas With and Without Smoothing Measured With Atomic Force Microscopy

PURPOSE

To analyze the surface roughness of porcine corneas after excimer laser ablation with and without the smoothing procedure by means of atomic force microscopy.

METHODS

Excimer laser photorefractive keratectomy (PRK) was performed on eight porcine corneas. Immediately following the procedure, smoothing was performed on four corneas using a viscous solution of 0.25% sodium hyaluronate. The corneas were examined in balanced salt solution after fixation in 2.5% glutaraldehyde solution using atomic force microscopy. Quantitative analysis of the ablated stromal surface topography was performed using the section analysis module of the atomic force microscopy software. Repeated measurements were made over small areas (< or =50 microm2) near the center of each ablation, with a vertical resolution of <1 nm.

RESULTS

Images of the ablated stromal surface showed undulations and granule-like features on the ablated surface of the specimens. The specimens on which the smoothing procedure was performed (root-mean-square [RMS] rough: 0.152 +/- 0.014 microm) were more regular (P < .001) than those on which PRK alone was performed (RMS rough: 0.229 +/- 0.018 microm).

CONCLUSIONS

Atomic force microscopy analysis requires a simpler preparation of the specimens with respect to that necessary for scanning electron microscopy; for this reason, atomic force microscopy techniques are more reliable for the study of biological surfaces and prove to be a feasible method to establish the differences when comparing different laser techniques. Our investigations highlight that although the laser cut of scanning-spot excimer laser systems is precise in removing even the smallest amounts of tissue, the smoothing technique may still be useful to reduce post-ablation roughness.

Corneal epithelial healing after photorefractive keratectomy: analytical study

PURPOSE

To characterize the velocity of epithelial migration after photorefractive keratectomy (PRK) with 3 different corneal ablation patterns.

SETTING

Department of Ophthalmology, Catholic University of Rome, Rome, Italy.

METHODS

Fifteen patients (30 eyes) with mild to moderate myopia and with simple to compound myopic astigmatism were enrolled for this study. The surgical procedure consisted of standardized PRK with final smoothing performed using the Technolas Keracor 217C excimer laser. The reepithelialization process was evaluated at 0 hours, 20 hours, 40 hours, and 60 hours after surgery using a digital photo camera and custom software for measurement. Digital analysis of the images was performed. Corneal topographies were taken at 1 month, 3 months, 6 months, and 12 months after PRK.

RESULTS

The mean speed of radial migration in the 10 eyes (33%) in the low spherical ablation group was 0.087 mm/h +/- 0.008 (SD). This was significantly higher than that found in the 10 eyes (33%) in the high spherical ablation group (mean speed 0.078 +/- 0.007 mm/h; P<.001) and in the 10 eyes (33%) in the cross-cylinder ablation group (mean speed 0.055 +/- 0.014 mm/h; P<.001).

CONCLUSION

Analysis of the data shows that epithelial migration along the photoablated corneal surface depends on the ablation pattern. The epithelial sliding is highly influenced by local variations in the curvature of the stromal surface. The data demonstrate that faster epithelial wound healing after PRK is predictive of optimal visual performance.

Heterogeneity in the ultrastructure of the mucous (goblet) cells of the rabbit palpebral conjunctiva

AIM

The purpose of this study was to assess objectively the ultrastructure of the secretory granules in rabbit conjunctival mucin-producing 'goblet' cells.

METHOD

The upper eyelids from five young adult dioestrous female rabbits were dissected out, stretched onto a cardboard support and prepared for transmission electron microscopy by repeated application of an isotonic two per cent glutaraldehyde fixative at room temperature. Post-fixation treatment included osmium tetroxide and staining with uranyl acetate and lead citrate. Low magnification micrographs were taken of the goblet cells of the conjunctiva, printed at a magnification of approximately 6,000 and the number, size and features of the secretory granules assessed.

RESULTS

Across the entire palpebral conjunctiva of all five rabbits, the majority of mucous cells displayed a goblet shape and the secretory granules were uniformly pale in staining. The average width of the goblet cells was 10.8 +/- 1.1 microm and the diameter of the secretory granules was 0.82 +/- 0.16 microm. However, in localised regions across the palpebral conjunctiva of two of the rabbits, some goblet cells were different in that the secretory granules had either a denser-staining core, in which some of the granules were densely staining (while others were pale) or most of the granules were densely staining. These mucous cells had an average diameter of 10.3 +/- 1.7 microm and the granule diameters averaged 0.88 +/- 0.01 microm. For these abnormal goblet cells, inflammatory cells were found in their immediate vicinity. Occasionally, goblet cells were seen to be in the process of degranulation with associated apparent cell necrosis and the mucin granule diameter was close to 1 microm.

CONCLUSIONS

The ultrastructure of the mucin-containing secretory granules of the conjunctival mucous cells is not necessarily homogeneous in character and further attention needs to be given to the effects of localised inflammation in the tissue and to possible hormonal influences.

Ocular surface changes with applanation contact lens and coupling fluid use after argon laser photocoagulation in noninsulin-dependent diabetes mellitus

PURPOSE

To describe the effect of coupling solutions used during laser photocoagulation on the ocular surface of patients with noninsulin-dependent diabetes mellitus (NIDDM).

DESIGN

A prospective case-controlled study.

METHODS

Ninety-two eyes of 46 NIDDM patients with clinically significant macular edema, poor metabolic control of diabetes, and peripheral neuropathy and 100 eyes of 50 normal control subjects were studied. The patients' eyes were assigned to argon green focal/grid laser photocoagulation using an applanation contact lens and one of the coupling fluids; 2% methocel, Thilo-Tears Gel, 1.4% sodium hyaluronate, or 0.9% simple saline. The control subjects received time-matched three-mirror contact lens fundus examinations. All subjects underwent corneal sensitivity measurements, Schirmer test, tear film breakup time, and corneal fluorescein staining before as well as 3 and 8 days after the laser procedures and contact lens examinations. Patients with corneal problems persisting after 8 days were followed longer.

RESULTS

Diabetic eyes assigned to 2% methocel and 1.4% sodium hyaluronate had significantly lower mean corneal sensitivities and break-up time values as well as significantly higher mean fluorescein staining scores at all examination points after laser photocoagulation. All diabetic eyes with aqueous deficiency assigned to 2% methocel and 1.4% sodium hyaluronate developed delayed corneal epithelial healing.

CONCLUSION

The use of viscous coupling solutions during applanation contact lens-aided laser procedures may be detrimental for the corneal epithelium in poorly controlled NIDDM patients with peripheral neuropathy and coexisting aqueous deficiency.

One-year Results of Photorefractive Keratectomy With and Without Surface Smoothing Using the Technolas 217C Laser

PURPOSE

To assess the efficacy, predictability, stability, and safety of a smoothing technique in patients with myopia immediately after photorefractive keratectomy (PRK) using a scanning-spot excimer laser.

METHODS

Using the Technolas 217C excimer laser, PRK was performed on 100 eyes of 54 patients. Ablation zone diameter was 6.0 mm and transition zone diameter was 9.0 mm. The eyes were randomized into two groups: in 50 eyes PRK alone was performed and in the other 50 eyes, a smoothing technique was performed after the initial ablation. Preoperative mean spherical equivalent refraction was -4.98 +/- 1.71 D in the PRK only group (range -2.25 to -8.60 D) and -4.82 +/- 1.61 D in the smoothing group (range -2.00 to -8.00 D). Follow-up was 12 months for all patients.

RESULTS

At 1 year after surgery, mean manifest spherical equivalent refraction was -0.61 +/- 0.50 D (range -2.25 to +0.62 D) in the PRK only group and in the smoothing group, +0.02 +/- 0.32 D (range -0.75 to +0.75 D). Postoperative regularity topographic indices were lower in the smoothing group than in the PRK group (P<.001).

CONCLUSIONS

Smoothing after PRK for correction of myopia up to -6.50 D increased surface regularity, as expressed by lower topography surface regularity indices, and reduced the incidence and severity of postoperative haze. We observed higher predictability throughout follow-up in the smoothing group, which may be addressed by a nomogram adjustment in the PRK only group.

Smoothing of the Ablated Porcine Anterior Corneal Surface Using the Technolas Keracor 217C and Nidek EC-5000 Excimer Lasers

PURPOSE

To demonstrate efficacy of a smoothing technique to increase regularity of the anterior corneal surface after photorefractive keratectomy (PRK), using two different excimer lasers.

METHODS

Spherical ablations of -10.00 D were performed on 11 fresh porcine corneas using either the Technolas Keracor 217C scanning-spot or the Nidek EC-5000 scanning-slit beam excimer laser. Following the procedure, we performed a phototherapeutic keratectomy treatment (smoothing technique) on half of the corneal surface. The smoothing technique was performed using a viscous solution of 0.25% sodium hyaluronate, which was spread on the cornea prior to the procedure. The ablation zone was 6 mm in diameter and the transition zone extended to 3 mm. The ablation depth was set at 10 microm. Corneas were then examined with scanning electron microscopy.

RESULTS

Smoother treatment zones were apparent in porcine corneas in which smoothing was performed following PRK, with both laser systems. Results from the two lasers were not directly compared.

CONCLUSIONS

The smoothing procedure performed following PRK using a viscous 0.25% sodium hyaluronate masking solution and a scanning laser system rendered the porcine corneal surface more regular.

Tear Function and Ocular Surface Changes with Topical Mitomycin (MMC) Treatment for Primary Corneal Intraepithelial Neoplasia

PURPOSE

To evaluate the tear function and ocular surface alterations in patients with primary CIN before and after treatment with topical mitomycin (MMC).

PATIENTS AND METHODS

We describe seven patients with unilateral CIN treated with 0.04% topical MMC three times daily until full eradication of the lesion. The patients underwent tear and ocular surface examinations including Cochet-Bonnet corneal sensitivity measurements, tear film break-up time (BUT), Schirmer test, and Rose-Bengal staining before, at the time of resolution of the CIN, and at the final follow-up. Conjunctival impression cytology was performed before treatment and at the last visit.

RESULTS

The mean pretreatment corneal sensitivity was 30.3 +/- 7.4 mm and improved to 55 +/- 5 mm at the final visit (P < 0.05). There were no aqueous-deficient eyes. The BUT values and Rose-Bengal staining scores also showed significant improvement at the last follow-up compared with the pretreatment values (P < 0.05). Initial impression cytology specimens showed goblet cell loss, higher grades of squamous metaplasia, areas of isolated keratinized, binucleated, and actively mitotic disfigured epithelial cells in all patients. The mean goblet cell density and squamous metaplasia grade were observed to improve significantly at the last visit (P < 0.05). MMC-induced cytologic changes were seen to persist long after cessation of treatment in some patients. All eyes remained free of recurrence and complications during the follow-up period.

CONCLUSION

We found 0.04% topical MMC treatment tid until full eradication to be effective in the management of CIN. The ocular surface disease of CIN was characterized by disturbance of tear film stability, goblet cell loss, and increased squamous metaplasia in all patients. Impression cytology proved useful in attaining the diagnosis of CIN, evaluating the effect of treatment, and showing MMC-related long-term changes on the ocular surface.

Surgical do's and don'ts of corneal dystrophies

PURPOSE OF REVIEW

Characteristics of corneal dystrophies have been described with regards to such as location in the cornea, morphology, material composition, and recurrence after penetrating keratoplasty. The main goal of this review is to describe the surgical methods in treating corneal dystrophies.

RECENT FINDINGS

Laser in situ keratomileusis (LASIK) has been shown to aggravate corneal deposits in Avellino dystrophy exacerbation LASIK and hence should be avoided. Phototherapeutic keratectomy (PTK) has shown its usefulness in clearing opacities with visual improvement and prevents painful erosion, resulting in delay or postponement of corneal grafting in some corneal dystrophies. Mitomycin-C may be used topically in conjunction with PTK to reduce the recurrence of the opacities. Topical use of antibody to TGF-beta can also be considered to suppress recurrence of corneal opacities after PTK or lamellar keratectomy.

SUMMARY

Clinicians must become more adept at choosing a treatment depending on different genotypes and future studies on treatment of corneal dystrophies should be focused on establishing treatment of categorized corneal dystrophies based on their chromosomal mutation.

Phototherapeutic keratectomy for BIGH3-linked corneal dystrophy recurring after penetrating keratoplasty

PURPOSE

To determine visual results and report side effects and complications after phototherapeutic keratectomy (PTK) for BIGH3-linked corneal dystrophy recurring after penetrating keratoplasty.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Forty-two excimer laser PTK procedures were performed in 42 eyes of 29 patients with BIGH3-linked corneal dystrophies. Genetic status of all patients was determined and allowed us to assess an unambiguous diagnosis. Preoperative diagnoses included LCDIIIA/A546T (1 eye), R124 l+DT125-DE126 (4 eyes), GICD/R555W (14 eyes), LCDI/R124C (6 eyes), SGD/R124 l (16 eyes), and CDBII/R555Q (1 eye).

INTERVENTION

Two excimer lasers (Summit Excimed UV 200, Summit Technology, Waltham, MA and Nidek EC 5000, Nidek, Inc., Gamagori, Japan) were used to perform all PTKs. Indications for performing PTK after a graft were severe decrease of the best-corrected visual acuity (BCVA) related to recurrent corneal deposits and/or painful recurrent epithelial erosions.

MAIN OUTCOME MEASURES

Preoperative and postoperative BCVA were analyzed, significant recurrences after treatment were noted, and postoperative complications were recorded.

RESULTS

Mean preoperative BCVA was 0.2 +/- 0.12 in the decimal chart, mean postoperative BCVA was 0.52 +/- 0.16 with a mean follow-up of 3.13 +/- 1.77 years (range, 0.3-6.65 years). Visual acuity was significantly improved after surgery (P < 0.05). The magnitude of the change in visual acuity was dependent on the mutation (P < 0.001). Seven symptomatic recurrences were observed. One regressive graft rejection and 4 cases of severe postoperative haze were observed. No other complications were noted.

CONCLUSIONS

PTK is a simple, safe, and efficient technique for the treatment of recurrent corneal dystrophies; in many cases it prevents or delays the major incumbent problems of repeated grafting.

Management of band keratopathy with excimer phototherapeutic keratectomy: visual, refractive, and symptomatic outcome

PURPOSE

To report on the outcome of excimer phototherapeutic keratectomy (PTK) in the management of band keratopathy.

METHODS

Analysis was performed on patients undergoing PTK for band keratopathy between January 1996 and December 1999. Patients were assessed as to whether the indication for PTK was for visual rehabilitation (visual group) or for ocular surface improvement (nonvisual group). Further data including pre- and postoperative best-corrected visual acuity, pre- and postoperative spherical equivalent (SE), and associated or previous ocular pathology were collected.

RESULTS

A total of 45 eyes of 33 patients underwent PTK for band keratopathy. In the visual group, there were 33 eyes of 22 patients, and in the nonvisual group 12 eyes of 11 patients. The visual acuity was improved or unchanged in 18/33 eyes (55%) of the visual group, while there was loss of one or more lines of acuity in 15/33 (45%). Loss of acuity was attributed to other factors in 11/15 eyes. There was a significant myopic shift (P<0.5) from the mean preoperative SE of +1.42 D (SD+/-3.21 D) to the mean postoperative SE of +0.32 (SD+/-3.26 D). Of the eyes in the nonvisual group, 10/12 (83%) had significant improvement of symptoms.

CONCLUSION

Excimer PTK is an effective procedure in the management of band keratopathy whether it is performed for visual rehabilitation or for ocular surface improvement to prevent erosions. Concurrent pathology is common and may limit the extent of visual improvement postoperatively. Factors associated with the myopic shift seen in this series may be epithelial remodelling, concurrent ocular pathology, or inaccuracy of preoperative refractive data.

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.

Ocular surface changes and tear film alterations associated with sun gazing during a solar eclipse

PURPOSE

A solar eclipse occurred in central Europe on August 11th, 1999. Following the eclipse, patients with ocular symptoms were investigated. Gazing at the sun without protection is liable to damage the retina. Our attention was focused on changes of the ocular surface and the tear film.

METHODS

Forty-three patients were investigated within one week after the solar eclipse as baseline. 33 of them were followed up one year later. Visual acuity and the central visual-field were measured, and the ocular surface and the fundus were examined using a slit lamp. The quality of the lacrimal tear film was examined using Schirmer's test for the aqueous layer, break-up time for the mucous layer and interference observation for the lipid layer, measured by a slit lamp and a tearoscope.

RESULTS

At the baseline 19 patients had non-specific visual problems. Pathological alterations of the tear film were seen in all three tear-film layers: Schirmer's test was pathological in 87%, break-up time decreased in 85%, the interference pattern of the lipid layer changed in 67% and there were changes in 87% using the tearoscope. One year later the non specific visual disorders had disappeared. Schirmer's test did not reveal much change from the baseline: 51% pathological, 24% remained pathological in break-up-time and the lipid layer was normalized except in 9%. Using the tearoscope, lipids were better than grade 3 in all patients.

CONCLUSION

After gazing at a solar eclipse the ocular surface and tear film changed. While the aqueous layer remained pathological in many patients, the lipid layer and the mucous layer recovered spontaneously.

Biomechanical Response of the Cornea to Phototherapeutic Keratectomy When Treated as a Fluid-filled Porous Material

PURPOSE

Surgical effect on corneal deformation has been traditionally analyzed based on the solid material assumption. We examine the validity of this assumption by treating the cornea as a fluid-filled porous material and separately modeling the solid and fluid constituents inside the cornea. In particular, the internal sub-atmospheric fluid pressure is treated as an important part of the mechanical loading in addition to the intraocular pressure.

METHODS

Finite element simulations of phototherapeutic keratectomy (PTK) were conducted with the cornea treated as a fluid-filled porous material, and through-the-thickness difference in swelling phenomena was taken into account. The results were compared with the same PTK simulations based on the solid material assumption of the cornea.

RESULTS

The PTK simulation results based on the fluid-filled porous material assumption demonstrated a significantly higher amount of unintended hyperopic shift compared to the results based on the traditional solid material assumption. The proposed approach qualitatively matched experimental observations.

CONCLUSIONS

The internal sub-atmospheric pressure significantly influenced corneal deformation. The simulation results based on the fluid-filled porous material assumption raise serious questions regarding the validity of existing models in corneal surgery, where the effect of the internal sub-atmospheric pressure on corneal deformations is neglected.

Excimer laser phototherapeutic keratectomy

Excimer laser phototherapeutic keratectomy (PTK) is an important tool in the management of superficial corneal pathology. It works well in the treatment of anterior corneal dystrophies and degenerations, but we are learning that it may have a role in the treatment of certain patients with deeper corneal pathology. Indications also are being expanded to treat much less common conditions and also to treat children. Irregular astigmatism, which is not treated very well with current PTK techniques, may be addressed better with newer approaches, such as selective zonal ablation and the use of BioMask. As current PTK techniques are improved and newer methods are developed, this procedure will continue to be an excellent option for certain patients with superficial corneal problems.

Refractive changes after excimer laser phototherapeutic keratectomy

PURPOSE

To study the visual and refractive changes in patients with superficial corneal opacities after excimer laser phototherapeutic keratectomy (PTK).

SETTING

Eye Clinic, Kobe Kaisei Hospital, Kobe, Japan.

METHODS

One hundred twelve eyes of 80 patients with superficial corneal opacities had PTK with the Nidek EC-5000 excimer laser system. All patients had routine ophthalmic examinations including uncorrected and Landolt best corrected visual acuity (BCVA) measurements, subjective and objective refractions, keratometry, EyeSys (Premier Laser Systems, Inc.) corneal topography performed before and 1 week and 1, 3, 6, and 12 months after PTK, and pachymetry performed before and 12 months after PTK. The change in refractive status within 12 months of PTK and the relationship between factors such as ablation depth, transition zone (TZ) setting, and use of masking agents and the amount of hyperopic shift were also assessed.

RESULTS

The BCVA increased by more than 2 lines in 65.1% of eyes and by 1 line in 24.1%. The BCVA did not change in 12 eyes (10.8%) because of cataract or underlying retinal disease. A mean hyperopic shift of 3.42 +/- 1.15 diopters (D) (range 1.00 to 5.25 D) was seen in all eyes at 12 months. The hyperopic shift peaked 1 month after PTK and tended to decline after that; it stabilized at 12 months.

CONCLUSION

Although PTK is a safe and efficient method for the treatment of superficial corneal opacities, induced hyperopia after the procedure remains a major problem. A shallow ablation depth (less than 100 microm), presence of a TZ setting, and use of a masking agent decrease the hyperopic shift significantly.

Alteration of the ocular surface with recurrence of granular/avellino corneal dystrophy after phototherapeutic keratectomy: report of five cases and literature review

PURPOSE

To study the changes in ocular surface findings with recurrence after phototherapeutic keratectomy (PTK) in patients with Avellino and granular dystrophy.

DESIGN

Observational case series.

PARTICIPANTS

Five eyes of five patients with recurrent granular/Avellino corneal dystrophy after PTK seen at Kobe Kaisei Hospital were studied.

INTERVENTION

The patients underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film breakup time (BUT), Schirmer test, tear film lipid layer interferometry, and conjunctival impression cytology.

MAIN OUTCOME MEASURES

The alterations of clinical features, tear function, and conjunctival impression cytology parameters with a recurrence after PTK were investigated.

RESULTS

The average pre-PTK corneal sensitivity and tear film breakup time were low in all five patients. Tear film lipid layer interferometry grade and conjunctival squamous metaplasia displayed higher grades before PTK. All of these parameters improved gradually after PTK and were maintained until a recurrence, which was associated with further worsening of the corneal sensitivity, tear function, and impression cytology parameters.

CONCLUSIONS

Although PTK improves the ocular surface health in granular/Avellino corneal dystrophies, recurrence of the initial dystrophy is associated with decline of the ocular surface health parameters. Our findings also suggest that corneal epithelium is most probably involved in the recurrence of the disease process in Avellino/granular corneal dystrophy.

Visual and tear function improvement after superficial phototherapeutic keratectomy (PTK) for mid-stromal corneal scarring

PURPOSE

To study the changes in visual and tear film function following superficial excimer laser phototherapeutic keratectomy in patients with mid-stromal corneal scars.

METHODS

Fourteen eyes of 14 patients with mid-stromal corneal scars seen at the Department of Ophthalmology at Kobe Kaisei Hospital underwent superficial phototherapeutic keratectomy (PTK). The subjects underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film break-up time (BUT), Schrimer test and tear film lipid layer interferometry. Thirty eyes of 15 normal control subjects were also studied. The patients and the control subjects were compared for pre-PTK tear function parameters and tear film lipid layer interferometry grade. The alterations in these parameters within 6 months following PTK were also determined.

RESULTS

Visual improvement was achieved in 12 eyes (86%). A hyperopic shift was observed in all eyes. The average pre-PTK corneal sensitivity and tear film BUT were lower in patients compared with control subjects before PTK. Tear film lipid layer interferometry grades were also higher in the patients than the controls before PTK. All these parameters improved gradually and significantly after PTK. Schirmer test results did not show any significant alterations after PTK.

CONCLUSION

We conclude that PTK is an effective means of treating corneal scars and attaining visual improvement, even in cases with deeper corneal involvement, and may obviate the need for corneal transplantation. Simultaneous improvements in corneal sensitivity and tear film stability suggest favourable effects of PTK on the ocular surface.