Correlation between fluorescein angiography, optical coherence topography and visual acuity in diffuse diabetic macular edema pre and post intravitreal injection of triamcinolone acetonide

To study the correlation between macular thickness by OCT, macular edema by FA and visual acuity finding in eyes with diffuse diabetic macular edema pre and after intravitreal injection of triamcinolone acetonide. This study included 40 eyes of 28 diabetic patients diagnosed as they had diabetic macular edema. Group I: included 20 eyes with primary diabetic macular edema. Group II: included 20 eyes with refractory diabetic macular edema. All patients received 4mg of intravitreal triamcinolone acetonide [IV TA]. Full ophthalmological examination. Fluorescein angiography and measurement of macular thickness [MT] by OCT were done to all cases preoperatively and 1.3 and 6 months postoperatively. Pre IVTA in group I: there was strong negative correlation between FA and VA[r/=-0.519] and weak correlation MT and VA[r=-0.421] while the correlation was positive between MT and VA[r=0.924]. In group II; there was negative correlation between FA,MT and VA[r=-0.594 and r=-0.672] but the correlation between MT and VA was positive, after IVTA allover the follow up period there was positive correlation between FA and MT in both groups. While the Correlation between BCVA and FA in Group I was negative correlation at 3rd and 6th month, the correlation in Group II was statistically non significant The correlation between MT and VA in group I was statistically significant 3 months after injection in both groups, however its effect decreases and recurrence of macular edema occurred 6 months after injection. In group II the correlation between MT and VA was statistically non significant. There is strong correlation between VA, OCT and fluorescein leakage. Visual acuity depends mainly on the macular perfusion not the amount of edema. OCT can differentiate between diffuse macular edema and cystoid macular edema diagnosed by fluorescein angiography

Actual versus expected Lasik flap thickness using the moria M2 130-microkeratome head

Aim: to evaluate actual versus expected laser in situ keratomileusis [LASIK] flap thickness using the Moria M2,130 microkeratome head

Methods: 50 eyes of 25 patients scheduled for LASIK surgery for myopia where enrolled in this study. Patients were prepared for surgery. On the day of surgery they were admitted to the LASIK room where the lids were sterilized and draped. A suction lid speculum was applied to one eye after instilling one drop of Benox into the conjunctiva2 sac, the eye was then washed with balanced salt solution BSS and the suction of the lid speculum activated to assure there was no excess BSS in the conjunctival sac then a final preoperative ultrasonic central corneal pachymetry reading using the sterile probe of the Tomey AL-2000 pachymetry was recorded. The suction ring of the Moria 1112 microkeratome was centered on the cornea and immediately after the lasilc3[lap was fashioned and the suction ring removed the flap was elevated then an intra operative central stromal bed pachmetry reading was recorded using the sterile Tomey AL- 2000 pachymetry probe. The actual flap thickness was calculated by subtracting the intra operative central stromal thickness from the preoperative central corneal thickness

Results: the mean actual flap thickness created by the Moria M2 130 head microkeratome for the first cut was 153.8 +/- 17 [range 120 micro m- 188pm] and for the second cut 148.4 +/- 15.82 [range 118- 185]. The mean difference in flap thickness between the3rst and second cur was 4.4 micro m 1.7 m with the tendency of the second flap to be slightly - thinner than the first. This difference was found to be statistically insignificant [P>0.05, paired t test]. The mean difference between the actual and expected flap thickness was 9.9 micro m +/- 1.7 and this was found to be statistically significant [P >0.001]

Conclusion: the difference between the actual and expected flap thickness using the Moria M2 microkeratome was statistically significant and care should be taken when making assumptions about flap thickness based upon the manufacturers labeling to calculate the residual bed thickness, having in mind that the flap may be thinner in some cases and thicker in others. The latter must be thought of well to avoid violating the rule of leaving at least 250 micro m of stromal bed after laser ablation, which may lead to postoperative ectasia , keratoconus and even intraoperative stromal penetration. It is recommended to do an intraoperative pachymetry in all LASIK cases if possible