PARTIAL TOPOGRAPHY-GUIDED PHOTOREFRACTIVE KERATECTOMY FOLLOWED BY CORNEAL CROSS LINKING IN THE MANAGEMENT OF PROGRESSIVE KERATOCONUS: OUR INITIAL TEN-MONTH RESULTS.

The aim was to assess the results achieved in keratoconic corneas submitted to the combined partial topography-guided photorefractive keratectomy (TG-PRK) and corneal cross linking (CXL) procedure performed on the same day. Four patients underwent this treatment of one eye. Corneal epithelium removal was performed by 50-micron phototherapeutic keratectomy. Then, partial TG-PRK laser treatment was applied (Wavelight Allegretto, Eye Q, 400Hz), followed by corneal collagen cross-linking (CXL, 3 mW/cm2) for 30 minutes using 0.1% topical riboflavin solution. Outcome measurements included uncorrected distance visual acuity (UCDVA), best spectacle corrected distance visual acuity (BSCDVA), manifest refraction spherical equivalent, keratometry, corneal high order aberration values, and corneal tomography. At the end of 10-month follow up, all eyes showed improvement in BSCDVA of 1-5 lines on Snellen chart. All other investigated parameters showed significant improvement as well. One eye showed some topographic improvement, but no improvement in UCDVA. No corneal haze, prolonged epithelial healing or endothelial cell loss occurred. During 10-month follow up, the same-day combined TG-PRK and CXL appeared to offer tomographic improvement and better visual acuity in keratoconus patients.

Sub-Bowman keratomileusis compared with photorefractive keratectomy--contralateral eye study.

The aim of this study was to compare two different refractive surgery approaches in correction of myopia with or without astigmatism. In patients where one eye underwent sub-Bowman keratomileusis (SBK) and the other eye photorefractive keratectomy (PRK), the objective and subjective results were retrospectively compared during the six-month follow-up. Eighty four patients (168 eyes) were involved in this retrospective contralateral study. The mean preoperative spherical refraction was -3.88 diopters (D) and the mean cylinder was -0.82 D for all eyes. Each patient underwent SBK on one eye and PRK on the contralateral eye. The eyes in the PRK group underwent mechanical epithelial removal, which was followed by laser treatment. Mitomycin C 0.02% was used for 15 seconds if ablation was deeper than 50 microns. In the SBK group, the intended 100-microm corneal flap was created with IntraLase femtosecond laser. All eyes underwent customized wavefront guided laser ablation using a VISX Star S4 IR excimer laser. Preoperative and postoperative outcome measures included best spectacle-corrected visual acuity, uncorrected visual acuity, corneal topography, contrast visual acuity, and anterior optical coherence tomography imaging. Patients were asked to complete subjective satisfaction questionnaires at each visit. Through the first 3 months of follow up, the SBK eyes demonstrated clinically and statistically better visual results than PRK eyes, between 3 and 6 months the results in the two groups began to equalize, and after 6 months of follow up there were no clinical and statistical differences between the SBK and PRK groups. SBK seems to be more practical for the patient with less pain, faster visual recovery, fewer medications, and overall superior experience.

Astigmatism and diagnostic procedures.

Astigmatism represents an inability of the cornea and lens to provide a sharp image onto the retina. Correcting astigmatic errors, whether congenital, contact lens induced or surgically induced, is now an integral part of modern cataract and refractive procedures. Development of modern technology has enabled accurate diagnosis and perfect opportunities for correction; however, while cataract and keratorefractive surgery have come a long way in the last decade, the treatment and diagnosis of astigmatism continue to challenge ophthalmologists. There are several diagnostic procedures and tools available today, some standard and some contemporary that include keratometry, corneal topography, apparatus using wavefront or Scheimpflug analysis like Orbscan, Pentacam, Wavescan, etc. With the introduction of several new diagnostic tools, measurements of astigmatism have become less of an issue, but in some cases it is still difficult to obtain consistent results. What remains still unanswered is the question of the best diagnostic tool on the market. Further research is needed to evaluate both tools as well as their clinical application for optimal use.