ABSTRACT
To evaluate the astigmatic correcting effect of paired opposite clear corneal incisions [OCCIs] on the steep axis in patients with residual astigmatism after laser in situ keratomileusis [LASIK] Thirty-one eyes of 24 patients with a mean age of 28.4 years +/- 2.46 [range, 19-36 years] were recruited for the study. Inclusion criteria included residual astigmatism of=1.5 diopter [D] after LASIK with inadequate residual stromal bed thickness that precluded ablation. The cohort was divided into two groups; group I [with astigmatism ranging from-1.5 D to-2.5 D] and group II [with astigmatism>-2.5 D]. The steep axis was marked prior to surgery. Paired three-step self-sealing opposite clear corneal incisions were performed 1-mm anterior to the limbus on the steep axis with 3.2-mm keratome for group I and 4.1 mm for group II. Patients were examined 1 day, 1 week, 1 month, 3 months and 6 months, postoperatively. Visual acuity, refraction, keratometry, and corneal topography were evaluated preoperatively and postoperatively. Analysis of the difference between groups was performed with the Student t-test. P<0.05 was considered statistically significant. The mean uncorrected visual acuity [UCVA] improved from 0.35 +/- 0.13 [range, 0.1-0.6] to 0.78 +/- 0.19 [range, 0.5-1] in group I and from 0.26 +/- 0.19 [range, 0.1-0.5] to 0.7 +/- 0.18 [range, 0.4-1] in group II. The increase in UCVA was statistically significant in both groups [P=0.001, both cases]. The mean preoperative and postoperative keratometric astigmatism in group I was 2.0 +/- 0.48 D [range, 1.5-2.5 D] and 0.8 +/- 0.37 D [range, 0.1-1.4 D], respectively. The decrease in keratometric astigmatism was highly statistically significant in group II [P=0.001.]. Mean surgically induced astigmatic reduction by vector analysis was 1.47 +/- 0.85 D and 2.21 +/- 0.97 D in groups I and II respectively. There were no incision-related complications. Conclusions: Paired OCCIs were predictable and effective in correcting post-LASIK astigmatism and required no extra surgical skill or expensive instruments. OCCIs are especially useful in eyes with insufficient corneal thickness for LASIK retreatment
ABSTRACT
Ketorolac tromethamine was formulated in different ophthalmic preparations namely; eye drops, gels, ocuserts and ointments using the following carriers; sodium carboxymethyl cellulose [sod. CMC], polyvinyl alcohol [PVA], hydroxypropylmethyl cellulose [HPMC], absorption base and gelatin. The ophthalmic formulations were prepared containing 0.5% of the drug. All prepared formulae containing the drug were subjected to stability study and release characteristics. Also, the effect of these drug carriers on the uptake and ocular disposition of ketorolac tromethamine by the eye tissues of rabbits [conjunctiva, cornea, iris-ciliary body and aqueous humor] was studied. The obtained results revealed that, the released amounts from the ophthalmic preparations after six hours can be arranged in the following order; Eye drops > ocuserts > gel > ointments. Sod CMC eye drops exhibited the higher rate of release than sod CMC gel, PVA and absorption base ointments. Gelatin ocuserts exhibited the higher rate of release than HPMC ocuserts and carbopol 934 and sod CMC ocuserts. The release rate of the drug from eye drops and PVA ointment obeys first order kinetics, while, other preparations obey Higuchi diffusion model with non-Fickian kinetics. Most formulations [including eye drops] could be stored for 6 months at 25°C, 35°C, 45°C without physical or chemical degradations of the drug. However, PVA and absorption bases showed some changes in the drug content [t[90] was 2.84 months for both at 45°C]. The decomposition rate ofketorolac tromethamine followed the first-order degradation kinetic. The highest stable formulae are, sod CMC eye drops and gel [t[90] values were, 151.9 and 91,18 months, respectively at 45°C]. The highest concentration of the drug [Cmax] from all tested formulations is provided in conjunctiva followed by cornea, iris-ciliary body, then aqueous humor. The peak time for maximum drug concentration [Tmax] from sod CMC eye drops was two hours. While, that for sod CMC gel, PVA ointment and gelatin ocuserts was three hours in all tissues after the application of the tested formulations. In addition, the total availability of the drug from the tested formulations was in the following order: gelatin ocuserts > sod CMC gel > PVA ointment > sod. CMC eye drops