Phototherapeutic keratectomy in the treatment of Avellino dystrophy

Long-term clinical outcome of femtosecond laser-assisted lamellar keratectomy with phototherapeutic keratectomy in anterior corneal stromal dystrophy

Purpose

To evaluate long-term outcome of femtosecond laser-assisted lamellar keratectomy (FLK) with phototherapeutic keratectomy (PTK) in patients with anterior corneal stromal dystrophies.

Methods

A total of 10 eyes from seven patients who underwent FLK were included. The patients had suffered from recurrent corneal erosion or visual disturbance in anterior corneal dystrophies (five Avellino dystrophies and two lattice dystrophies). Planar-shaped lamellar keratectomy was performed using femtosecond laser. The amount of corneal excision was determined by the depth of corneal opacity. Additional PTK with mitomycin C application was performed for smoothening of corneal cut surface. The patients were evaluated with following parameters: uncorrected visual acuity, best-corrected visual acuity (BCVA), mean anterior keratometric value, corneal irregularity, corneal high-order aberrations (HOA) and the recurrence of corneal erosion.

Results

Mean duration of follow-up was 64 months (2.5–9.5 years). The BCVA improved more than two lines of Snellen chart at last visit. The changes of keratometric values were within ±1 D in eight out of 10 eyes. Corneal irregularities in central 5 mm cornea and the values of total corneal HOA in central 6 mm cornea decreased by 0.3–3.1 D and 0.01–2.2 µm, respectively. Corneal erosion did not recur in any of those patients during follow-up and corneal dystrophy did not recur in eight out of 10 eyes.

Conclusion

In anterior corneal stromal dystrophies, FLK with PTK can be an effective surgical option to improve VA through decreasing corneal irregularities and HOA, while minimising corneal curvature changes.

Outcomes of photorefractive keratectomy instead of phototherapeutic keratectomy for patients with granular corneal dystrophy type 2

PURPOSE

The purpose of this study was to evaluate visual function and postoperative refractive errors in patients with granular corneal dystrophy type 2 (GCD2) and cataracts who underwent photorefractive keratectomy (PRK) instead of phototherapeutic keratectomy (PTK) following cataract surgery to avoid PTK-induced central island formation and reduce refractive errors after cataract surgery.

METHODS

The medical records of 14 eyes from nine patients (one man and eight women; mean age, 69.0 ± 8.5 years) with GCD2 and cataracts were evaluated. All patients underwent PTK using the PRK mode 3 months after cataract surgery. We analyzed corrected distance visual acuity (CDVA), refractive errors, and corneal astigmatism derived from Fourier analysis and assessed the incidence of complications in cataract surgery and PTK.

RESULTS

The mean CDVA logMAR values were 0.42 ± 0.19, 0.38 ± 0.18, and 0.16 ± 0.12 before and after cataract surgery and after PTK, respectively. CDVA improved significantly after PTK, as compared with both before and after cataract surgery (P < 0.001). The mean absolute errors after cataract surgery and PTK were 0.53 ± 0.43 and 1.61 ± 1.01 diopters, respectively. Pre- and postoperative Fourier indices did not significantly vary in the 3-mm diameter zone, and only the asymmetry component of the 6-mm diameter zone significantly (P <0.01) increased postoperatively. No central island formation and no other marked complications were observed postoperatively in any case.

CONCLUSIONS

Performing PTK using the PRK mode following cataract surgery may be effective for patients with GCD2 and cataracts.

IOL power calculation after corneal refractive surgery

PURPOSE

To describe the different formulas that try to overcome the problem of calculating the intraocular lens (IOL) power in patients that underwent corneal refractive surgery (CRS).

METHODS

A Pubmed literature search review of all published articles, on keyword associated with IOL power calculation and corneal refractive surgery, as well as the reference lists of retrieved articles, was performed.

RESULTS

A total of 33 peer reviewed articles dealing with methods that try to overcome the problem of calculating the IOL power in patients that underwent CRS were found. According to the information needed to try to overcome this problem, the methods were divided in two main categories: 18 methods were based on the knowledge of the patient clinical history and 15 methods that do not require such knowledge. The first group was further divided into five subgroups based on the parameters needed to make such calculation.

CONCLUSION

In the light of our findings, to avoid postoperative nasty surprises, we suggest using only those methods that have shown good results in a large number of patients, possibly by averaging the results obtained with these methods.

Analysis of deposit depth and morphology in granular corneal dystrophy type 2 using fourier domain optical coherence tomography

PURPOSE

Granular corneal dystrophy type 2 (GCD2) causes the formation of corneal deposits having 3 different morphological types. We used Fourier domain optical coherence tomography to assess the depths of each type according to the morphology.

METHODS

A prospective study was performed in 54 eyes of 54 heterozygous patients with GCD2. Corneal deposits of 54 patients with GCD2 were classified into 3 morphological types: type 1, diffuse haze; type 2, granular shape (2 subgroups: type 2a, round granulated and type 2b, round spiculated); and type 3, linear shape (2 subgroups: type 3a, short side branched and type 3b, long side branched). Using Fourier domain optical coherence tomography, we measured the distances from the Bowman layer to the upper surface of the deposits (USBL), to the lower surface of the deposits (LSBL), and the thickness of the deposits (TD). The deposits formed along the flap interface were also examined among 19 patients who had LASIK.

RESULTS

Types 1 and 2 deposits were always adjacent to the Bowman layer; thus the USBLs for each were 0.0 ± 0.0 μm, whereas that of type 3 deposits was 65.4 ± 48.0 μm (P < 0.0001). The LSBL and TD of linear deposits with long side branches (type 3) (313.3 ± 71.4 and 246.2 ± 71.9 μm) were greater than those of type 1 (47.7 ± 10.2 and 47.7 ± 10.2 μm) and type 2 (91.3 ± 39.5 and 91.3 ± 39.5 μm) (P < 0.0001). There were no differences in the measurements between the subgroups type 2a and type 2b or between types 3a and 3b. USBL of the laser in situ keratomileusis group was 54.5 ± 29.8 μm.

CONCLUSIONS

The depths of corneal deposits in patients with GCD2 were associated with the morphology of the deposits. The linear deposits were located most deeply in the cornea, followed by granular deposits and diffuse haze moving anteriorly. Several deposits have distinct depths according to the morphological types.

Phototherapeutic Keratectomy for Relief of Pain in Patients With Pseudophakic Corneal Edema

PURPOSE

To evaluate the therapeutic effects of phototherapeutic keratectomy in patients with pseudophakic corneal edema

METHODS

Phototherapeutic keratectomy was performed in 12 eyes of 12 patients with pseudophakic corneal edema who were awaiting penetrating keratoplasty. All patients underwent planned corneal ablation of 120 microm. Examinations before and after surgery included uncorrected and corrected visual acuity, slit-lamp biomicroscopy, photography, and ultrasonic pachymetry.

METHODS

A reduction in pain and a slight increase in visual acuity as well as a decrease in corneal thickness were found over an average 18-month follow-up period (range, 6 to 60 months).

CONCLUSIONS

Phototherapeutic keratectomy reduced bullae formation, improved visual acuity slightly, and could be considered a valuable alternative to penetrating keratoplasty if surgery needs to be delayed or is contraindicated.

Genetics of the corneal dystrophies: what we have learned in the past twenty-five years

PURPOSE

To indicate important changes in our understanding of the corneal dystrophies.

METHODS

A review of the literature of the last quarter of a century.

RESULTS

The earliest clinical classifications of the corneal dystrophies were based on the application of clinical, biological, histochemical, and ultrastructural methods. Since then, the first great impetus to our understanding has come from the application of techniques to map disorders to specific chromosome loci, using polymorphic markers. More recently, using candidate gene and related approaches, it has been possible to identify genes causing several of the corneal dystrophies and the mutations responsible for their phenotypic variation. A notable success has been to show that several important "stromal" dystrophies result from mutations in the gene beta ig-h3, which encodes for the protein keratoepithelin (beta ig-h3).

CONCLUSIONS

For the corneal dystrophies, as with other inherited disorders, there is room for two sorts of classification system, one based mainly on clinical presentation and the other on an up-to-date understanding of the genetic mechanisms. They are not mutually exclusive. Some developmental corneal disorders are also discussed.

Granular dystrophy of the cornea

BACKGROUND: Granular corneal dystrophy is the commonest of the dystrophies and usually results in visual disability in the fourth or fifth decades. CASE HISTORY: A patient with granular corneal dystrophy is reported and the clinical characteristics described. DISCUSSION: The classical clinical features and the pathology and management of granular dystrophy are reviewed. Two unusual variations of the corneal dystrophy, namely, juvenile granular dystrophy and Avellino dystrophy, which is a concurrence of the features of granular and lattice dystrophies, are also described.

Heterogeneity in granular corneal dystrophy: identification of three causative mutations in the TGFBI (BIGH3) gene-lessons for corneal amyloidogenesis

Six autosomal dominant corneal dystrophies are caused by mutations in the TGFBI (BIGH3) gene on chromosome 5q31: three types of lattice corneal dystrophy (LCD), including type I and type IIIA, granular, Avellino (ACD), and Reis-Bucklers. Initially an exact genotype-phenotype correlation was reported. We report three families, with differing clinical features, all presenting with "granular" corneal dystrophy. We analysed the TGFBI gene by SSCP analysis and direct sequencing in order to further assess the genotype-phenotype correlation. We describe three separate mutations in TGFBI: one novel, one initially described as causing ACD, and one previously described. The novel mutation, R124S, is at the identical position to the mutation causing LCD type I (CDL1). We review the clinical and histological phenotypes of the corneal dystrophies and hypothesize that the ability of a mutation to cause amyloid deposition depends on the location and nature of the mutation. In addition, we suggest that the classification of the granular corneal dystrophies be revised according to mutation type and that ACD should not be classified as a distinct morphological entity.

Therapeutic use of the 193-nm excimer laser in corneal pathologies

PURPOSE

To analyze the results of phototherapeutic keratectomy.

PATIENTS AND METHODS

We performed 193-nm excimer laser phototherapeutic keratectomy (PTK) in 252 eyes of 216 patients suffering from pain and/or decrease in visual acuity. One hundred and three eyes had recurrent erosions of the cornea, 86 eyes underwent excimer laser smoothing of the cornea after pterygium surgery, 29 eyes had a bandlike keratopathy (25 rough, 4 smooth) and 34 eyes had other pathologic conditions such as amyloidosis of the cornea, anterior corneal dystrophies, scars after injuries, alkali burns, superficial stromal dystrophies and infections. Recurrent erosions and epithelial dystrophies were treated with 15-20 pulses (160-200 mJ/cm2, 8 mm ablation zone) after mechanical abrasion of the epithelium. Removal of corneal opacities and scars required the use of a masking fluid (methyl-cellulose) in different concentrations and slit-lamp control (integrated in the delivery system of the excimer laser).

RESULTS

Some 91% of the eyes with recurrent erosions were recurrence-free. Fifty-two per cent of the eyes with pterygium had recurrences if the baresclera technique was used and 33% of the eyes if a free conjunctival graft was used. The difference was not significant. All of the patients with bandlike keratopathy were pain-free. In 88% of the eyes with special indications the treatment goal was achieved. No positive effect was seen after alkali burn, in a patient with anterior membrane dystrophy (Grayson-Wilbrandt corneal dystrophy) or in a patient with a corneal protuberance. In one patient with scleroperikeratitis a late recurrence of the opacity was observed 3 years after surgery. A loss of best corrected visual acuity was found only in one patient with bullous keratopathy in whom the treatment goal was the reduction of pain. All patients with smooth bandlike keratopathy had an improvement in best corrected visual acuity of at least one line. About 70% of patients with special indications improved by at least one line, up to nine lines. A possible hyperopic shift in all groups could be minimized using a large ablation zone.

CONCLUSION

PTK with the 193-nm excimer laser is a safe and effective treatment for many superficial diseases of the cornea.