الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Corneal collagen cross-linking (CXL) is a bioengineering technique to increase the mechanical stability of the cornea in corneal ectatic disorders such as keratoconus (KC).
One technological improvement is the introduction of UV-A delivery devices with higher irradiance output (9–45 mW/cm2). Higher irradiance UV-A delivery devices have been introduced to shorten irradiation time to as little as 160 seconds. Based on Bunsen-Roscoe law of reciprocity (the effect of a photochemical reaction is directly proportional to total irradiation dose irrespective of time).
Accelerated cross-linking is similar to the standard riboflavin/UV cross-linking procedure now in widespread clinical use, but the riboflavin presoak and UV exposure times are significantly shortened and the UV irradiance is increased.
An additional opportunity for increasing the efficiency of CXL procedures may be as simple as turning the UV-A beam on and off at a specific time intervals. This allows oxygen to diffuse to the stroma without being depleted by the photochemical mechanisms that occur while the beam is on.
The aim of this work was to evaluate the safety and efficacy of continuous VS pulsed light accelerated corneal collagen cross-linking on patients with progressive keratoconus.
Patients underwent clinical examination of UCVA, BCVA, keratometric measurement (K1, K2, K mean), central corneal thickness and corneal densitometry, preoperatively and for 6 months postoperatively.
Informed consent was obtained from all study participants.
Our results summarized that
The study included 40 eyes of 25 patients, the group I (CL-ACXL) includes 20 eyes of 12 patients (6 male and 6 female). The mean age was 24.6±3.65 with range from 19-28 years, in group II (PL-ACXL) includes 20 eyes of 13 patients (6 male and 7 female), and the mean age was 25.1±4.65 with range from 18-30 years.
There were statistically significant improvements in both groups between preoperative and postoperative UCVA as well as BCVA in both groups. No statistical significant differences between the two groups at different periods of follow-up.
There were no statistically significant differences in both groups between preoperative and postoperative K1, as well as in between the two groups at different periods of follow-up.
There were no statistically significant difference in both groups between preoperative and postoperative K2, but there were statistically significant difference in between the two groups at 1, 3, and 6 month.
There were no statistically significant difference in both groups between preoperative and postoperative Kmean, but there were statistically significant difference in between the two groups at 3rd month.
There were no statistically significant differences in both groups between preoperative and postoperative central corneal thickness, as well as in between the two groups at different periods of follow-up