1. “Development of Unilateral Corneal Ectasia After PRK with Ipsilateral Preoperative Forme Fruste Keratoconus” Jacob Reznik, MD¹; James J. Salz, MD²; Alena Klimava, MS³. 1. Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA 2. Laser Vision Medical Associates, Cedars Sinai Medical Center, Los Angeles, CA, USA 3. The Johns Hopkins University School of Medicine, Baltimore, MD, USA Corresponding author: Jacob Reznik, MD Wilmer Ophthalmological Institute Johns Hopkins University 600 N. Wolfe Street, Wilmer B27 Baltimore, MD 21287 E-mail: jreznik1@jhmi.edu Phone: (410)955-5700 Fax: (410)955-0046 The authors have no proprietary interest in the materials presented herein.

2. Abstract: Purpose: To describe clinical and topographic features of a prominent keratectasia after photorefractive keratectomy (PRK) in a patient with abnormal preoperative topography. Methods: A 25-year-old man underwent bilateral uneventful PRK for moderate myopia of - 5.75 - 1.75 x 95 OD and - 7.50 -1.25 x 80 OS with BSCVA 20/25 OU. Preoperative corneal pachymetry was 500 μm OD and 460 μm OS. The total calculated ablation depth was 70 μm in the right eye and 100 μm in the left eye. Preoperative corneal topography revealed forme fruste keratoconus (FFK) OD with I-S ratio of 4. Results: 5 years postoperatively, the patient developed unilateral inferior keratectasia OD with refraction of + 0.50 - 5.50 x 90 with BSCVA of 20/100 and central pachymetry of 481 μm with inferior pachymetry of 374 μm. Conclusion: This case reports adds to the growing body of evidence in the ophthalmic literature suggesting that patients with preoperative FFK or early keratoconus may develop clinically-significant progression of corneal ectaisa after PRK.

3. Case report: A 25-year-old man was evaluated for refractive surgery to correct moderate myopia. The patient denied previous contact lens wear and his ocular history was otherwise unremarkable. No previous history of chronic eye rubbing, other trauma, or atopy was reported. No family history of corneal ectasia was reported. No signs of clinical keratoconus were seen on slit-lamp biomicroscopy. Dilated funduscopic examination was within normal limits. BSCVA was 20/25 in both eyes with a refraction of - 5.75 - 1.75 x 95 OD and - 7.50 - 1.25 x 80 OS. Preoperative central corneal pachymetry was 500 μm OD and 460 μm OS. Keratometry readings were 42.50/42.25 x 90 OD and 43.25/44.00 x 90 OS with no distortion of the keratometer mires OU. No clinical signs of keratoconus were observed with slit-lamp biomicroscopy in both eyes. Corneal topography (Optikon 2000) was normal OS and abnormal OD with obvious inferior steepening and I-S ratio of 4. (Figure 1). The abnormal topography was discussed with the patient. He was informed that laser in situ keratomileusis (LASIK) was absolutely contraindicated secondary to abnormal topographic findings. He was informed that if he agreed to PRK this might accelerate the progression of keratectasia and if this did in fact happen, he would most likely require a hard contact lens and possibly even a penetrating keratoplasty. On 4/1/98, patient received -6.86 -0.75 X 180 excimer laser correction with the Visx Star laser (VISX Inc., Santa Clara, California, USA) with ablation zone 6.0 x 5.7 mm for ellipse and 5.5 mm for sphere OS; 303 pulses were administered. The fellow eye was similarly treated on 5/27/98 with correction of - 4.71 -2.33 X 90; ablation zone of 6.0 mm x 4.9 mm; 435 pulses were administered. The total calculated ablation depth was 70 μm in the right eye and 100 μm in the left eye.

4. The early postoperative course was uneventful. 6 weeks after the procedure, UCVA was 20/20 OU, and BSCVA OD was 20/15 (plano -0.25 X 35). Slit-lamp biomicroscopy was normal OU. At 5 years follow up UCVA was CF at 6 feet OD and 20/40 OS. BSCVA was 20/25 OD with refraction of +0.50 -5.50 x 90 and 20/20 with refraction of -1.00 sphere OS. Corneal pachymetry OD was 481 μm centrally and 374 μm inferiorly. With preoperative pachymetry of 500 μm OD, we thought the postoperative values might have been related to a combination of corneal epithelial hyperplasia and new collagen deposition. Pachymetry of the fellow eye was 450 μm centrally and 450 μm inferiorly. Corneal topography (Zeiss Hymphrey Systems) showed marked inferior steepening OD and was normal topography in the fellow eye. (Figure 2) The patient underwent Intacs (Addition Technology, Inc.) insertion with IntraLase femtosecond laser (IntraLase Corp.) channels OD in 01/2005. Most recent follow up in 04/06 revealed UCVA CF at 6 feet OD. BSCVA was 20/70 with - 3.50 - 2.25 x 105. The fellow eye remained stable both topographically and clinically. (Figure 2) Patient was referred for SynergEyes (SynergEyes Inc., Carlsbad, CA) contact lens fit. (Figure 3) SynergEyes is a hybrid contact lens made of a rigid gas permeable (RGP) center fused to a soft, hydrophilic outer skirt. This design is thought to provide vision correction through the central RGP portion of the lens combined with a soft periphery to bear the weight and improve centration qualities. BCVA with SynergEyes contact lens in our patient was 20/20-2 OD with plano over-refraction. Topography OD again showed inferior steepening. (Figure 4) Topography with the SynergEyes contact lens in place showed a marked improvement in the corneal contour. (Figure 5)

5. Discussion: Keratectasia is a known major complication of LASIK. To date, over 100 cases have been reported in refractive surgery literature (1). Several preoperative risk factors have been proposed for keratectasia after LASIK, such as high myopia, forme fruste keratoconus (FFK), and low residual stromal bed, but cases with mild myopia, normal topography, and residual stromal bed >300 μm also may develop ectasia. (2,3) Keratectasia is also one of the most difficult post-LASIK complications to manage; current options include RGP contact lenses, intracorneal rings, phakic toric IOLs and lamellar or penetrating keratoplasty (4,5,6). Even though the upper limit of myopia suitable for treatment by LASIK has been arbitrarily set as -12.0, keratectasia cases after LASIK was noted in cases treated for much lower degrees of myopia, from –4.0 to –7.0 D (7). Inferior corneal steepening was noted in some of these cases pre-operatively. In the absence of refractive instability or biomicroscopic features of keratoconus these corneal changes have been termed forme fruste keratoconus (FFK) (8). There are a few case reports indicating good long-term refractive outcomes and corneal stability after PRK in such cases as compared to LASIK (9,10). One study of a corneal forward shift after PRK using a scanning-slit corneal topography found that these changes usually stabilize 6 months after surgery (11). A more recent case report described a patient with thin central corneas (485 microns in the right eye and 500 microns in the left eye) and corneal topography revealing asymmetric bow-tie astigmatism with inferior steepening in the right eye and a small area of inferior steepening in the left eye, who underwent a PARK in the right eye and LASIK in the fellow eye (12). Both eyes had similar myopic and astigmatic refractive error. 22 months postoperatively, patient developed keratectasia in the post-LASIK eye; post-PARK fellow eye remained stable both clinically and topographically. The authors have concluded that PARK/PRK may be a safer procedure, especially in the eyes with pre-operative risk factors.

6. Discussion (continued): Our patient had a clear preoperative FFK in the right eye and normal topography in the left eye. His other risk factors included BSCVA of less than 20/20 and relatively thin corneas. He elected to proceed with bilateral PRK and had developed progressive corneal changes consistent with clinical keratoconus in the right eye. The left eye has remained stable over the period of 7 years in regards to visual acuity, corneal topography and biomicroscopic findings. The question to ask here is would this patient have developed progression of FFK in the right eye without PRK? Previous studies have clearly demonstrated spontaneous progression of FFK into clinical keratoconus (13). Our patient has developed progressive unilateral corneal changes after PRK. His refraction has been stable in that eye for several years preoperatively. It is not unreasonable to suggest that post-PRK biomechanical corneal weakening had accelerated progression of unilateral FFK to clinical keratoconus. A recent longitudinal study of keratoconus patients concluded that around 50% of clinically normal fellow eyes will progress to keratoconus in 16 years. (14) It is also not unreasonable to theorize that out patient may still develop clinical keratoconus in the fellow eye in the future. This case report illustrates that in FFK may progress to clinical keratoconus after PRK procedure. A few recent publications have advocated choosing PRK over LASIK for patients with preoperative risk factors for developing corneal ectasia. Moreover, a recent article by Bahar et. al. (15) suggested that a wavefront supported PRK appears to be effective for treatment of myopia and astigmatism in patients with suspected keratoconus and thin, irregular corneas. Authors suggest that patients in whom LASIK surgery is contraindicated because of suspected FFK, especially when the I-S difference is greater than1.5 D, are good candidates for wavefront-supported PRK treatment, as it saves ablated tissue and treats corneal surface irregularities. A major drawback of the study remains short-term (less then 40 months) follow up (less then 40 months).

7. Discussion (continued): We conclude that the issue of PRK safety over LASIK for patients with FFK and thin, irregular corneas needs to be studied further before any recommendations of its preference is universally accepted. In addition, a careful preoperative discussion, clinical evaluation and informed consent are of a paramount importance for patients with preoperative risk factors who desire refractive surgery, either LASIK or PRK.

10. Figure 3

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