Differential Diagnosis of Atypical Brown Syndrome and Primary Inferior Rectus Restriction of Double Elevator Palsy

Both atypical Brown syndrome (ABS) and inferior rectus restriction of double elevator palsy (DEP) are characterized by monocular limitations of upgaze in primary, abducted position as well as abducted position. Futhermore, they exhibit resistance of elevation in adduction during forced duction test and should be considered in the differential diagnosis. We gained several differential points from 6 year-old female with ABS and a 12 year-old female with DEP due to inferior rectus restriction (IRR). In forced duction test under general anesthesia, ABS exhibited resistance of elevation in adduction and IRR of DEP showed resistance of elevation in all upward direction. DEP showed an impairment of Bell`s phenomenon and mild pseudoptosis preoperatively in which ABS never showed. ABS displayed divergence in upgaze producing V-pattern, and further limitation of upgaze in adduction than DEP. Superior oblique lengthening procedure using silicone expander was performed for ABS. Ipsilateral inferior rectus and contralateral superior rectus recession were performed for IRR of DEP. The results for elevation in adduction, primary position and abduction were satisfactory in both diseases. In conclusion, the direction of resistance in forced duction test, Bell` s phenomenon, the degree of elevation in abducted and abducted position, presence of pseudoptosis and divergence in upgaze producing 3 V-pattern may be helpful to differentiate ABS from IRR of DEP.

Changes in Aqueous Nitric Oxide Concentration Following Excimer Laser Corneal Ablation

There have been some reports about formation of free radical species in aqueous humor after excimer laser photorefractive keratectomy(PRK). We investigated whether there exists an increase of nitric oxied(NO) level in aqueous humor after excimer laser treatment. Of the 41 albino rabbits(81 eyes) used for this study, 25 eyes served as controls. The remaining 56 eyes were divided into three groups, i.e., a group with its epithelium removed mechanically(3 eyes), -6.0D PRK group(24 eyes) and -12.0D PRK group(29 eyes). After varing time intervals following excimer laser treatment, aqueous NO concentration was determined with ELISA method using Griess reagent. The mean aqueous NO concertration was 101.83ng/ml in normal control group and showed no difference(107.00ng/ml) from that of mechanically abladed group, Aqueous NO was increased 30 min after PRK in both groups compared to normal(-6.0D : 218.67ng/ml, -12.0D : 198.68ng/ml) and maintained at one hour postoperatively. Eyes with -12.0D ablation still while eyes with -6.0D ablation showed no difference from normal. Six hours after PRK, aqueous NO was returned to the normal level in both groups of PRK. The results of this study showed that excimer laser PRK induced NO production in aqueous humor, and the more extensive amount of excimer laser applied, the longer time would be taken to restore the normal NO level. It seems that such an elevation of NO level could be one of the factors that cause temporary corneal stromal edema or anterior chamber reaction after excimer laser PRK.