Dr. Sudhank Bharti, B02433, Dr. Raka Bharti, Dr. Bhupesh Singh
Phacoemulsification requires a dilated pupil for successful completion of cataract removal. A well dilated pupil is necessary for appropriately sized capsulorrhexis, nuclear management, complete cortical removal and in the bag IOL insertion. A small pupil may result in damage to iris tissue leading to inflammation, corneal and macular oedema and consequent poor visual recovery. Pupil dilation is poor in cases of Diabetes, after long term use of miotics and selective alpha blockers for prostate hypertrophy and anterior uveitis. Pupil expansion devices may damage the sphincter pupillae leading to a semi dilated pupil postoperatively causing photophobia and an unhappy patient. Various pupil expansion devices- Iris hooks, Malyugin ring, Assia pupil expander, Oasis pupil expander and B-Hex pupil expander were used in minimum 3 cases for cataract surgery. All cases where inflammation was the cause of small pupil were excluded from this study. A preop pupil size in photopic conditions was measured with OPD Scan 3 (Nidek,Japan) and compared with pupil size at 1 month post op. A comparison of 1 month postop pupil size determines the device which causes the least trauma to the sphincter pupillae.
Material and Methods:
23 eyes of 23 patients were taken into this study. The patients were posted for Cataract surgery with phacoemulsification and were diagnosed with non dilating pupil with a combination of Tropicamide and Phenylepherine eye drops during first examination .
On the day of surgery the pupil size of the eye for surgery was examined with OPD Scan 3 and as per standard protocol Phynelepherine 5% + Tropicamide 1% eye drops were instilled every 15 minutes for 4 times under blood pressure monitoring.
The mean preop pupil size was 3.63 mm (+/- 1.24 mm).
All the eyes were operated by a single surgeon ( SB ) and devices used were randomly assigned .
3 eyes had Assia Pupil Expander (APX) , 3 eyes had Oasis Pupil expander , Iris hooks were used in 4 eyes, Malyugin ring was used in 6 eyes and B Hex pupil expander in 7 eyes.
The patients were kept on topical antibiotics, steroids, mydriatics, Nepafenac, hypertonic saline drops and betoxolol for 7 days. Topical mydriatics and hypertonic saline eye drops were discontinued after 1 week and steroid eye drops in tapering dose along with nepafenac eye drops 2 time a day and betoxolol eye drops 2 times a day were continued for 3 weeks.
The topical treatment was discontinued completely at 1 month.
On the 1 month postoperative visit the pupil size was measured again with OPD Scan 3.
A total of 23 eyes with rigid non dilating pupils were included.
The 3 eyes in which Assia pupil expander (dilates pupil to a 6 mm square/rectangle ) was used had a mean pupil diameter 3.66 preoperatively and 4.37 mm at 1 month postoperative.
In the 3 eyes where Oasis expander ring ( Dilates pupil to 7 mm) was used the mean pupil diameter was 3.61 preoperatively and 4.28 postoperatively.
In the 4 eyes receiving Iris Hooks for pupil dilation during Phacoemulsification( Pupil dilation 6-7.5 mm) the mean pupil diameter preoperatively was 3.91 mm and postop mean pupil diameter was 4.98 mm
In the 6 eyes in which Malyugin ring was used ( Pupil Dilation 6 mm) the mean preoperative pupil diameter was 3.74 preoperatively and 3.99 postoperatively.
In the 7 eyes where B_Hex pupil expander was used ( pupil dilation 6-7mm, device used 6 mm ) the preoperative pupil size was 4.06 preoperative and 4.32 postoperatively.
A dilated pupil with a minimum size of 5 mm persisting throughout the phacoemulsification procedure is desirable for achieving safe, smooth and successful procedure causing no damage to the Iris muscles and endothelium and providing good visibility of posterior capsule.
Several strategies to dilate a small pupil are in use. Visco dilation of the pupil, Sphincterotomis and stretching the pupil with Kuglen hooks were used initially before advent of pupil expansion devices. Visco dilation is shortlasting and both sphincterotomies and hooks damage the sphincterpupillae muscles thereby causing large pupils post operatively leading to dysphotopsiae.
We used pupil dilation devices in small pupils due to non inflammatory causes like Diabetes, Pseudo exfoliation syndrome, Long term use of miotics and oral alpha blockers and cases of nondilating pupils in previous intraocular surgeries.
The pupil has a dynamic character and keeps on changing it’s size according to the ambient light conditions and any damage to the structure can reduce or abolish this character. A constantly enlarged pupil is a source of photophobia and dysphotopsiae.
Any pupil expansion device loses it’s utility if it damages the sphincter pupillae muscle.
Both Malyugin ring and Bhattacharjee pupil expander are least traumatic to the sphincter pupillae as compared to Assia pupil expander tends to stretch the pupillary muscle at 4 points and causes damage to this muscle. The Oasis Iris Expander is a bulkier device and stretches the iris muscle all round and causes a nonreacting middilated pupil. The Iris hooks are most damaging to the iris muscle and they stretch the pupil at the points of touch causing depigmentations and a large pupil.
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