Contraindications of Refractive Surgery in Upper Egypt

1. Contraindications of Refractive Surgery in Upper Egypt Engy Mohamed MD. PhD. MD. PhD Sohag University Egypt No author has a financial or proprietary interest in any material or method mentioned.

2. Laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) have gained popularity as the surgical procedures of choice for the correction of refractive errors. • The safety and efficacy of LASIK and PRK are well established.

3. Meticulous pre-operative screening of potential candidates is a key factor contributing to successful outcomes in refractive surgery. • A candidate for refractive surgery must undergo a comprehensive ophthalmic examination.

4. Parameters used for patient selection for keratorefractive surgery • Age 18 years or older • Stable refraction for the previous year or longer • Absence of any corneal pathology (keratoconus - forme-fruste keratoconus- Pellucid marginal degeneration) • Absence of any other ocular pathology • Anterior corneal elevation < 12µm • Posterior corneal elevation <18µm • Absence of medical contraindications • No pregnancy or lactation

5. LASIK • Myopia of up to -12.00 Diopters • Astigmatism <4.00 Diopters • Hyperopia <4.00 Diopters • Central corneal thickness (CCT) of >480 μm • Residual stromal bed thickness (RSB) of >280 μm

6. PRK • Myopia of up to -5.00 Diopters (D) • Astigmatism <2.00 Diopters • CCT of >460 μm • Remaining corneal thickness >400 μm

7. Patients approaching presbyopic age were informed about the requirement of wearing spectacles for near correction. • Patients were instructed to stop using their soft and hard contact lenses for at least 2 weeks and 4 weeks respectively before submitting to preoperative examination.

8. Aim of the Work • Causes of inability to perform LASIK and PRK surgeries in patients seeking refractive surgery in Sohag city, Southern of Egypt.

9. MATERIALS AND METHODS • This is a retrospective observational study. • Approved by the Research and Ethics Committee of Sohag University Hospital. • The clinical and investigational findings were reviewed and the reasons for not performing keratorefractive surgery (LASIK or PRK) were recorded and analyzed.

10. The medical records of 2663 consecutive patients who presented for a refractive consultation at the Sohag refractive center, between January 2011 and December 2011 were reviewed.

11. Pre-operative data • Uncorrected visual acuity (UCVA) • Best spectacle-corrected visual acuity (BSCVA) • Refractive error (subjective and cycloplegic) • Schimpflug topography by Sirius (CSO, Italy) • Slitlampbiomicroscopy • Dilated retinal exam

12. The Sirius combines a rotating Scheimpflug camera and a small-angle Placido-disk topographer with 22 rings. The scanning process acquires a series of 25 Scheimpflug images (meridians) and 1 Placido top-view image.

13. Analysis of present data was performed using software version 1.0 and included: -Mean simulated K -Anterior and posterior corneal elevation -Minimum corneal thickness

14. Three topographic measurements of each eye were performed and the technician chose the image with the widest corneal coverage for processing. • If artifacts were present on the raw images (mire reflection) or on the color-coded topographic maps, the measurement was repeated.

15. RESULTS

16. Out of the 2663 patients, 622 patients (23.35%) were not found to be candidates for either LASIK or PRK.

17. From these 622 patients, 375(60.28%) were females. • Mean age was 28±10.8 years. • Age ranges from 18-62yrs.

18. Contraindication to Keratorefractive surgery

19. Keratorefractive causes (80.5%) • Other ocular intities (12.9%) • Systemic causes (6.6%)

22. Patients with topographic signs of keratoconus, forme-fruste keratoconus or pellucid marginal degeneration in one eye were denied surgery.

25. Discussion

26. Over One-fifth of the patients (23.3%) who presented to our refractive surgery unit were advised not to undergo keratorefractive surgery.

27. In this series, high myopia (greater than -12.0 Diopters) was the most common reason (17.4%) for not offering patients keratorefractive surgery. • Keratoconus was the second most common reason and accounted for 15%.

28. In populations with a high prevalence of consanguinity, the incidence of genetic disease is higher than usually found. Several cases have been reported in the literature of keratoconus in children of consanguineous parents (Bechara et al 1996)

29. If we sum all corneal topography abnormalities, i.e. keratoconus, keratoconus suspect, elevated anterior or posterior corneal elevation, pellucid marginal degeneration and suspicious topography, they all together accounted for 43.7% of the cases that were poor candidates for keratorefractive surgery

30. In general, the majority of our patients had satisfactory outcomes. For those patients who are not suitable for keratorefractive surgery, other alternative refractive procedures such as phakic intraocular lens implantation and clear lens extraction should be presented.

31. Recommendations • Careful screening reduces suboptimal results and avoids frustration for both the refractive surgeon and patient. • Refractive surgeons should be meticulous in evaluating corneal topography to detect features consistent with adverse outcomes.

32. Thank you