Picture illustration
Case #20
The patient
ILLUSTRATIONPRK on bilateral stable Keratoconus induced by eye rubbing
Identity : Ms O.F
First visit : 08/05/2013
Last Visit : 01/25/2017
Surgery : PRK at 12/15/2016
38
Age (years)41
Follow-up (months)Ms. O.F is a 38-year-old female with no previous medical history other than atopy. She has no known family history of keratoconus. She had been seen at another institution for a refractive surgery suitability assessment and was informed that LASIK « was unsafe because of the corneas ». She came to us of a second opinion, hoping for some refractive surgical option as she preferred not to wear glasses (due to aesthetic and functional reasons) and was no longer comfortable with contact lenses.
Her refraction at the first visit (08/05th/2013) was: Right Eye (RE) 20/20 with -5 (-0,25 x 55 °) and Left Eye (LE) 20/20 with -4.5 (-0,5 x 130 °)
Clinical examination with the slit lamp was normal in both eyes.
Corneal topography revealed the presence of bilateral inferior keratoconus, with more pronounced steepening in the right eye.
When asked about the possibility of frequent eye rubbing, the patient admitted to rubbing her eyes frequently every day, especially when working in front of the computer, because she enjoyed it.
We explained to the patient that the topographic changes in her were a consequence of her eye rubbing habit, and told her to stop rubbing her eyes immediately. We also explained that we had to document topographic stability after cessation of eye rubbing before the idea of refractive surgery could be entertained. We advised her against LASIK as there was a high risk of worsening of the corneal deformation with the procedure. From our experience and from many reports in the literature, Photorefractive Keratectomy (PRK) is not contraindicated in such cases with mild myopia, especially if the topography shows stability of at least one year. We also explained in detail to her that eye rubbing after PRK could compromise the outcome of the procedure.
At her 3rd visit, 3 years after her first consultation, corneal stability using difference maps was clearly demonstrable. We then performed bilateral PRK (on 12,15th/2016).
Three months after the PRK her refraction was : RE 20/20 with -0.25 (-0.25 x 140°) and LE 20/20 with -0.25 (-0.5 x 25°) .
Here are pictures of the patient rubbing her eyes and her profiles
ILLUSTRATIONHere are the Orbscan quadmaps with the SCORE Analyser results , OPDscan (topography and aberrometry) maps and the Ocular Response Analyzer (ORA) results of the first visit .
ORBSCAN RIGHT EYE. Note on the curvature map (bottom left), a slight infero-temporal steepening. The thickness map (bottom right) shows centro-temporal thinning.
LEFT EYE ORBSCAN. This examination is almost unremarkable, but on the curvature map (bottom left), a slight inferior steepening is noticeable. The thickness map (bottom right) shows centro-temporal thinning.
RIGHT EYE SCORE Analyzer. From the Orbscan data, this software based on automated linear discriminant analysis for keratoconus diagnosis computes a value, which is positive here.
LEFT EYE SCORE Analyzer. From the Orbscan data, this software based on automated linear discriminant analysis for keratoconus diagnosis computes a value, which is positive here.
RIGHT EYE OPD. Note the high order aberration.
LEFT EYE OPD. Note high order aberration.
RIGHT EYE ORA. The biomechanical examination reveals low applanation peaks, indicating a "locally more deformable" cornea.
LEFT EYE ORA. The biomechanical examination reveals low applanation peaks, indicating a "locally more deformable" cornea.Difference maps were performed at each subsequent visit. No evolution was observed between the first and last visits. The keratoconus is stable, more than 4 years since the first visit and 1 month since the PRK after the patient definitively stopped rubbing her eyes .
BEFORE PRK SURGERY
2013 to 2016
RIGHT EYE ORBSCAN (2nd VISIT). There is marked irregularity on the curvature map (bottom right), and the cornea is thin (pachymetry map, bottom left). The anterior elevation map (top left) shows increased prolateness (negative asphericity).
LEFT EYE ORBSCAN (2nd VISIT). The cornea is thin, and there is an "asymetric bow tie" (inferior steepening) on the curvature map (bottom left).
RIGHT EYE ORBSCAN (3rd VISIT)
LEFT EYE ORBSCAN (3rd VISIT)
RIGHT EYE PENTACAM (3rd VISIT) : Belin/Ambrósio Enhanced Ectasia display from the Oculus Pentacam
LEFT EYE PENTACAM (3rd VISIT) : Belin/Ambrósio Enhanced Ectasia display from the Oculus Pentacam
RIGHT EYE PENTACAM DIFFERENTIAL MAPS : PACHYMETRY (performed between 2013 to 2016). There is absolutely no progression over the years.
LEFT EYE PENTACAM DIFFERENTIAL MAPS : PACHYMETRY (between 2013 to 2016). This difference map shows no evolution from 2013 to 2016, from the time the patient stopped rubbing her eyes.AFTER PRK SURGERY
at 12/15/2016
RIGHT EYE PENTACAM : 1 month post PRK 
LEFT EYE PENTACAM : 1 month post PRK This case is both informative and intriguing. It is debatable whether it is legitimate to perform PRK on proven or suspected keratoconus cases. This is one of the grey zones of refractive surgery!
Our experience shows that performing laser surface ablation (PRK, with no flap cut) in such instances is safe for the cornea provided the patient has understood the stakes involved in eye rubbing after surgery. We also found that PRK creates a similar surgical environment to cross-linking without endothelial toxicity and much less keratocyte apoptosis (cellular death). PRK may not induce much of a stiffening effect, but the inflammation generated by the laser and by the stromo-epithelial healing response may generate a slightly different (reduced) corneal sensitivity in the long run. This surgically induced cornea desensitisation (like in cross-linking), together with post-operative pain and the fear of poor surgical outcome or failure are major deterrents to eye rubbing.
In the literature, the cases of post-PRK ectasia are very scarce, and it appears that the prevalence of ectasia in the operated population is less than the prevalence of keratoconus in the non-operated population.
Explaining the deleterious effects of chronic and vigorous eye rubbing to refractive surgery candidates is one of the most important steps in the prevent of post-surgical corneal ectasia.
- Date 15 août 2017
- Tags Computer screen, Enjoyed eye rubbing, Eye rubbing, Female, PRK, Work rubbing