الفهرس 
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Abstract
English Summary
For a long time, many trials have been done in order to correct refractive errors. This was either with classical approaches such as spectacles and contact lenses or by refractive surgeries which have become an acceptable alternative for a large number of patients and surgeons over the past three decades.
LASIK and phakic IOLs with its different types have become one of these surgical alternatives. The present work studied the effects of Lasik, posterior chamber P-IOL (ICL) and iris-fixated anterior chamber P-IOL on contrast sensitivity.
LASIK is the most common surgery used to correct myopia, in which a flap is created and the cornea is ablated with the excimer laser, irrigated with BSS, and the flap is reapplied again on the cornea.
Phakic IOLs demonstrate reversibility, high optical quality, and potential gain in visual acuity in myopic patients due to retinal magnification; they are not limited by corneal thickness or topography.
Contrast sensitivity is an important factor to assess the quality of vision. CSF is often more sensitive to visual disturbances than other means of visual assessment. Diminished contrast sensitivity may cause decreased visual function in spite of normal visual acuity.
Our study included sixty eyes with moderate to high myopia. Twenty eyes, with spherical error ranging from -5.00 to -7.50 diopters were corrected by LASIK. Another twenty eyes, with spherical error ranging from -7.00 to - 23.00 diopters were implanted with ICL. Last twenty eyes, with spherical error ranging from - 6.00 to -18.00 diopters were implanted with iris claw.
In all types; the surgery was safe, effective, and predictable with insignificant low complication rate. It also provided rapid visual rehabilitation and long term stability.
Follow up of these eyes has been done for three months postoperative. We found that, The BCVA improved one to two lines from the preoperative values in all types and the refractive results were stable.
Pupil ovalization was reported only in one eye in case of iris claw lens and was visually insignificant.
One eye only implanted with ICL developed crystalline lens opacity which was due to low vault, excluded from the study.
In this prospective study, we evaluated the postoperative changes regarding contrast sensitivity between LASIK, ICL and iris claw
In group A (patients underwent LASIK surgery):
Postoperative measurements after one month showed increase in CS thresholds at all spatial frequencies that reached significant values at 3,12 c/d(P=0.042, 0.008) in comparison with preoperative values. After three months more increase in CS threshold value, significant difference was found at 1.5, 3and 12 c/d spatial frequency.
In group B (patients underwent ICL surgery):
Postoperative measurements after one month, there were some increase in CS thresholds at all spatial frequencies that didn’t reach significant values. After three months a significant increase in CS threshold value, was found at all spatial frequencies in comparison with preoperative values.
In group C (patients underwent iris claw surgery):
Post operative measurements after one month showed significant increase in CS threshold values at all spatial frequencies in comparison with preoperative values. After three months a more significant increase in CS threshold values, was found at all spatial frequencies.
Regarding ACD; a sufficient Anterior Chamber Depth is necessary. ACD less than 2.8mm measured from the endothelium was considered a limitation for both Iris claw and ICL. So we recommend Iris claw and ICL implantation in eyes with ACD 2.8 mm or more.
Regarding the pupil size; which acts as an important factor in preventing postoperative glare and halos, VeriFlex, having a larger optic (6.0mm), is recommended in eyes with larger mesopic pupil diameter.
In order to avoid implantation of undersized or oversized ICL and to prevent postoperative rotation or decentration of the P-IOL, accurate preoperative white to white measurement using the Scheimpflug photography or a caliper is mandatory.
A peripheral iridectomy is mandatory to prevent pupillary block glaucoma. Performing an ”intraoperative” peripheral iridectomy for both types of Iris claw lenses by scissors is better than a preoperative Nd: YAG which might be small and insufficient. In cases with ICL we use the generations of V4C which has central micro central hole acting as peripheral iridotomy.
In addition; a thorough preoperative and postoperative fundoscopic examination was required to rule out retinal changes or vitreoretinal pathologies and to perform prophylactic laser photocoagulation, if required.
In conclusion, the results of all groups in our study were satisfactory with success rate of at least 80%. Patients who had LASIK had a higher success rate and their results were more stable throughout the follow up period. In phakic IOL the CST increased postoperative in both groups but in Iris claw group show more increase in CST which was more significant.