Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration

AIM

To investigate the influence of tilt and decentration of scleral-sutured intraocular lenses (IOLs) on ocular higher-order wavefront aberrations.

METHODS

In 45 eyes of 36 patients who had undergone scleral suture fixation of posterior chamber IOL, tilt and decentration of IOLs were determined by Scheimpflug videophotography, and higher-order aberration for a 4-mm pupil was measured using the Hartmann-Shack aberrometer. In another 100 eyes of 100 patients after standard cataract surgery with posterior chamber IOL implantation, ocular higher-order aberration was measured.

RESULTS

In eyes with scleral-sutured IOL, the mean (SD) tilt angle and decentration were 4.43 degrees (3.02 degrees ) and 0.279 (0.162) mm, respectively. Ocular coma-like aberration in the sutured IOL group was 0.324 (0.170) microm, which was significantly greater than that of the standard cataract surgery group (0.169 (0.061) microm, p<0.001, Student's t test). No significant difference was found in ocular spherical-like aberration between the sutured IOL group (0.142 (0.065) microm) and standard surgery group (0.126 (0.033) microm; p = 0.254). In the sutured IOL group, IOL tilt significantly correlated with ocular coma-like aberration (Pearson's correlation coefficient r = 0.628, p<0.001), but no significant correlation was found between IOL tilt and ocular spherical-like aberration (r = 0.222, p = 0.175). The IOL tilt did not correlate with corneal coma-like (r = 0.289, p = 0.171) and spherical-like (r = 0.150, p = 0.356) aberrations. The IOL decentration did not correlate with any higher-order aberrations.

CONCLUSION

In eyes with scleral-sutured posterior chamber IOL, tilting of the lens induces considerable amount of ocular coma-like aberrations.

Regular and irregular astigmatism after superior versus temporal scleral incision cataract surgery

OBJECTIVE

To evaluate the effect of superior and temporal scleral incisions on regular and irregular astigmatism in small incision cataract surgery.

DESIGN

Prospective, randomized, comparative clinical trial.

PARTICIPANTS

One hundred seventy-four eyes of 87 patients with bilateral cataracts scheduled to undergo routine cataract surgery.

METHODS

One eye of each patient was randomly assigned to the superior incision group, and the contralateral eye was allocated to the temporal incision group. Phacoemulsification and intraocular lens implantation were performed through an unsutured 4.1-mm scleral incision. Patients were examined 1 day and 1, 3, and 6 months after surgery.

MAIN OUTCOME MEASURES

Surgically-induced regular astigmatism calculated with vector analysis method, irregular astigmatism obtained by Fourier analysis of videokeratography data, and uncorrected and corrected visual acuity.

RESULTS

Postoperatively, the superior incision group showed slight against-the-rule astigmatic changes, whereas slight with-the-rule astigmatism was seen in the temporal incision group. The amount of against-the-wound astigmatism and absolute value of length of the induced vector did not differ significantly between groups (P > 0.05, paired t test). In both groups, irregular astigmatism 1 day after surgery was significantly greater than the preoperative levels (P < 0.001), but not thereafter. No significant intergroup difference was observed in the amount of irregular astigmatism at any postoperative visits (P > 0.05). There was no significant difference in uncorrected and corrected visual acuity between groups postoperatively (P > 0.05, chi-square test).

CONCLUSIONS

In small scleral incision cataract surgery, superior and temporal approaches are comparable in terms of visual rehabilitation and induction of regular and irregular astigmatism.

Inhibition of intraocular proliferations with intravitreal corticosteroids

Autotransplantation of one fourth million tissue cultured fibroblasts from rabbit rump skin into the vitreous cavity resulted in intravitreal strand formation and traction retinal detachment (27 of 47 eyes, 57%). A single intravitreal injection of 1 mg of dexamethasone alcohol inhibited fibroblast growth as judged by the significantly reduced number of retinal detachments (11 of 46 eyes, 24%). Retinal neovascularization that was observed when fibrous strands came into contact with vascularized retina (nine of 47 eyes, 19%) was also inhibited after corticosteroid application (two of 46 eyes, 4%).

Intravitreal autotransplantation of fibroblasts

Tissue cultured skin fibroblasts autotransplanted into the vitreous cavity of rabbit eyes formed intravitreal strands that grew toward the medullary ray and optic nerve head and caused preretinal puckers and traction detachment. After four weeks, 32 of 51 eyes (63%) developed these changes. Light and electron microscopy revealed initial cell death. Remaining cells aligned themselves quickly into strands and began to multiply as shown by tritiated thymidine methyl incorporation. The appearance of cells that resemble myofibroblasts may explain the contractability of the strand. Because the effect of intraocular proliferation can be quantitated by the number of puckers and retinal detachments developing, this model may be useful for the study of therapeutic means to reduce intraocular proliferation.

Treatment of intraocular proliferations with intravitreal steroids

Autotransplantation of 250,000 tissue cultured fibroblasts from rabbit rump skin into the vitreous cavity results in intravitreal strand formation and traction retinal detachment (27 of 47 eyes, 57%). A single intravitreal injection of 1 mg of dexamethasone alcohol inhibits fibroblast growth as judged by the significantly reduced number of retinal detachments (11 of 46 eyes, 24%).