Posters

Topography-guided Transepithelial Photorefractive Keratectomy to regularize corneal surface followed by subsequent phacoemulsification and monofocal IOL implant in pre-treated radial keratotomy eyes

Poster Details

First Author: S.Giugno ITALY

Co Author(s):                        

Abstract Details

Purpose:

Radial Keratotomy is a refractive technique to correct myopia not used anymore because of unpredictable long term effects such as irregular astigmatism, increased spherical aberrations, corneal ectasia. Excimer lasers are now the gold standard for treating refractive errors and regularize corneal surface in order to reduce corneal aberrations and achieve an optimal optical zone. I aimed to correct long-term effects of Radial Keratotomy by topo-guided Transepithelial Photorefractive Keratectomy (TG-TPRK) in 12 eyes of 6 patients showing irregular cornea and high order aberrations. Subsequently phacoemulsification and monofocal IOL implant was performed in order to remove cataract and correct myopic refractive errors

Setting:

Studio Oculistico Dott. Salvatore Giugno, Viale Mario Gori 63, 93015 Niscemi (CL)

Methods:

I evaluated 12 eyes of 6 patients who received radial keratotomy 20 years before for a myopic refractive error. Median age was 55 SD 8 years; BCVA was 1.00 +/- 0.1 log MAR (+1.67 +/- 1.5 SE), 12 radial keratotomies were present, crystallines were opacified: N2 C2 P0 to N4 C3 P2 (Locks III classification) Mean keratometry values, summary of aberrations, corneal astigmatism were acquired (Sirius CSO); COMA, spherical aberrations, total Trefoil, irregular optical zone were present; preoperative pachymetry was 597 +/- 85 microns. It was performed TPRK treatment + 0.02% MMC and 6 months later a phacoemulsification + IOL

Results:

TG- TPRK addressed corneal aberrations and not refractive errors; in order to achieve a prolate cornea, it was set an hypermetropic refraction correction to allow excimer laser to act in the cornea periphery. Intended laser ablation was 77 +/- 25 microns in the centre and 162 +/- 80 microns in the cornea periphery. After treatment 0.02% MMC was applied for 2 minutes in all eyes in order to prevent haze formation followed by corneal irrigation with 50 ml of balance salt solution. Patients eyes were evaluated at one, 3 and 6 months; significant improvement was seen in: mean K1 from 38.03 +/- 1.87 D to 42.70 +/- 2.67 D mean K2 from 41.79 +/- 1.15 D to 43.59 +/- 0.95 D @125 corneal spherical aberrations: from 2.7 +/- 2 μm to -0.05 +/- 0.45 μm COMA from 1.49 +/- 2.07 μm to 0.3 +/- 0.42 μm Trefoil: from 1.10 +/- 0.4 μm to 0.40 +/- 0.18 μm. Residual stromal thickness was 512 +/- 54 microns. Spherical equivalent shifted toward a moderate myopic value: -4.75 +/- 3.75 D. Phacoemulsification and monofocal IOL implant was performed 6 months after TG-TPRK targeting emmetropia; for IOL calculation Barrett true K formula and Sirius CSO Ray tracing were used. Phacoemulsification and implantation of monofocal IOL in the capsular bag was performed with a standard technique: no complications were encountered. Post surgery mean spherical equivalent was +0.5 +/- 0.5 D

Conclusions:

TG-TPRK with 0.02 % MMC is a reliable method for correcting post-RK cases with irregular astigmatism and elevated higher-order aberrations before cataract surgery in order to obtain not only a reduction of night glares, halos and an increased contrast sensitivity but also a more precise IOL calculation because of a more uniform optical zone. TG-TPRK has proven to be effective in restoring a prolate corneal shape and even if a temporary increase in refractive defect occurred, it was corrected implanting a monofocal IOL during cataract surgery.

Financial Disclosure:

None