Related Experiment Videos
Posterior corneal surface changes after refractive surgery
E Hernández-Quintela1, S Samapunphong, B F Khan
1Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA.
Ophthalmology
|July 27, 2001
Summary
Changes in the posterior cornea after laser vision correction (LASIK and PRK) were similar to natural variations observed in non-surgery eyes. This suggests refractive surgery does not significantly alter posterior corneal curvature beyond expected changes.
Area of Science:
- Ophthalmology
- Corneal Surgery
- Refractive Surgery
Background:
- Laser vision correction procedures like LASIK and PRK aim to reshape the cornea for improved vision.
- Understanding changes to the posterior corneal surface is crucial for assessing refractive surgery outcomes and safety.
- Previous studies have focused more on anterior corneal changes, leaving posterior surface alterations less understood.
Purpose of the Study:
- To quantify the frequency and nature of posterior corneal surface changes following photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).
- To compare these changes against natural variations in posterior corneal curvature over time in a control group.
Main Methods:
- A nonrandomized, comparative trial involving 95 eyes (71 patients) undergoing PRK (45 eyes) or LASIK (50 eyes).
- Posterior corneal curvature (PCC) was analyzed using elevation topography maps and compared between pre- and post-operative states.
- Two analysis methods (float and apex-fixed best fit corneal curvature - ABC) were employed across various zone diameters, with comparisons to 70 non-surgery eyes.
Main Results:
- Both PRK and LASIK groups exhibited flattening, steepening, and no significant change in PCC, with variations depending on the analysis method used.
- For PRK, the float method showed 22.2% flattening, 53.3% no change, and 24.4% steepening; the ABC method showed 28.9% flattening, 35.6% no change, and 35.6% steepening.
- For LASIK, the float method showed 20% flattening, 52% no change, and 28% steepening; the ABC method showed 30% flattening, 40% no change, and 30% steepening.
- The non-surgery control group demonstrated similar degrees of PCC change over time, indicating natural variability.
Conclusions:
- The observed changes in posterior corneal curvature after PRK and LASIK were not statistically different from the natural variations seen in the control group.
- This suggests that refractive surgery, within the parameters studied, does not induce significant, abnormal changes in the posterior corneal surface.
- The findings support the safety profile of PRK and LASIK concerning posterior corneal biomechanics.