Year : 1994 | Volume
: 42 | Issue : 3 | Page : 133--137
Effect of flurbiprofen sodium on pupillary dilatation during scleral buckling surgery
TK Roysarkar, S Mitra, MP Shanmugam, KV Ravishankar, Radha Murugesan
Sankara Nethralaya, Medical Research Foundation, Madras, India
K V Ravishankar
Sankara Nethralaya, Medical Research Foundation, 18 College Road, Madras 600 006
Maintenance of pupillary dilatation is necessary for success of scleral buckling procedures. The efficacy of 0.03% flurbiprofen in preventing intraoperative miosis was evaluated by a prospective randomized, double-masked controlled trial of 60 patients. Thirty patients received 0.03% flurbiprofen 6 times at 15 minute intervals 90 minutes preoperatively in addition to the routine dilation regimen. The treated group had a mean pupillary decrease of 1.88 mm and the control group had a decrease of 1.57 mm (p > 0.05). Flurbiprofen did not affect the pupillary size at any step of the surgery. Factors such as age of the patient, lens status, number of cryo applications, duration of surgery, and the size and extent of buckle were assessed. The use of flurbiprofen did not affect the mean pupillary change for any of these groups. Preoperative use of flurbiprofen does not significantly decrease intraoperative miosis during scleral buckling procedures
|How to cite this article:|
Roysarkar T K, Mitra S, Shanmugam M P, Ravishankar K V, Murugesan R. Effect of flurbiprofen sodium on pupillary dilatation during scleral buckling surgery.Indian J Ophthalmol 1994;42:133-137
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Roysarkar T K, Mitra S, Shanmugam M P, Ravishankar K V, Murugesan R. Effect of flurbiprofen sodium on pupillary dilatation during scleral buckling surgery. Indian J Ophthalmol [serial online] 1994 [cited 2022 Dec 5 ];42:133-137
Available from: https://www.ijo.in/text.asp?1994/42/3/133/25573
Miosis during retinal detachment surgery may prevent adequate visualisation of the retinal periphery, thereby compromising the success of scleral buckling. Topical mydriatic solutions are used to obtain sufficient preoperative dilatation but it is equally important to maintain the dilatation for the duration of surgery. Methods like pupillary stretching by fixation sutures,  iris retractors sphincterotomies, and iris cutting with vitrectomy probes can be used to dilate the pupil intraoperatively but they involve intraocular procedures which cannot be used in routine scleral buckling procedure.
Pharmocologic agents are the natural choice for maintaining mydriasis and various agents have been studied in animal models , and human eyes.  Since intraoperative pupillary constriction is mediated by prostaglandin (PG) release,  prostaglandin inhibitors like flurbiprofen should theoretically be useful in preventing intraoperative miosis.  It has been conclusively shown that flurbiprofen is effective in inhibiting surgically induced miosis in human eyes undergoing cataract extraction.  Hence, we undertook a prospective, controlled, randomized, double-masked trial to determine if flurbiprofen is useful in preventing intraoperative miosis during scleral buckling surgery.
MATERIALS AND METHODS
Seventy-six patients undergoing routine scleral buckling from mid-December 1992 to mid-February 1993 at our institute were considered for enrolment in the study. Institutional research board approval was obtained.
Preoperative exclusion criteria included sector iridectorny, anterior or posterior synechiae, irisfixated IOL, or elevated blood pressure that precluded use of preoperative phenylephrine drops. Intraoperative exclusion criteria included use of intracameral adrenaline, or use of air/gas after drainage of subretinal fluid in aphakic eye.
All patients included in this study received routine preoperative dilation with 2% homatropine hydrobromide and 10% phenylephrine hydrochloride. Additionally, patients randomly assigned to treatment group also received 0.03% flurbiprofen 6 times every 15 minutes starting 90 minutes preoperatively. The surgeon was unaware of the treatment assignment. Preoperative data included the patient's age, gender, laterality, the lens status, history of previous intraocular surgery, and history of previous scleral buckling surgery.
In the operating room, the pupillary diameter was measured under the operating microscope by the surgeon, after insertion of an eyelid speculum with a calliper accurate to 0.5 mm. The horizontal diameter only was measured. For eyes with oval pupil, the longest diameter was measured. Additional steps at which the pupillary diameter measurement was taken were: (1) following opening the conjunctiva and muscle tagging, (2) following cryopexy and localization of retinal breaks, (3) following subretinal fluid drainage and temporary placement of buckle, and (4) following conjunctival closure. All patients had 360° conjunctival opening with placement of #240 encircling band. Other intraoperative details recorded were: (1) number of cryo applications, (2) the extent and the size of buckle (3) drainage or nondrainage procedure, (4) duration of surgery, (5) type of anaesthesia: local or general (6) paracentesis done or not, and (7) whether surgery could be completed inspite of miosis.
Statistical analysis was done by chi-square test, Student's t-test, and paired t-test.
Seventy-six patients underwent scleral buckling surgery between mid-December 1992 and midFebruary 1993 at our institute. Of these 76 patients, 16 patients were excluded. because of sector iridectomy (8 patients), posterior synechiae (2 patients), use of intracameral adrenaline (4 patients), and use of air after drainage of subretinal fluid in aphakic eye (2 patients). Thus, a total of 60 patients were eligible for this study.
Of the 60 patients, 44 were males and 16 were females. The mean patient age was 43.8 years. Thirty patients were randomized to receive flurbiprofen and 30 patients were randomized to receive routine preoperative dilatation only. Effectiveness of randomization was assessed using the chi-square method and no statistically significant difference was found between the treatment and control groups for age, sex, lens status, previous intraocular or buckle surgery, duration of surgery, size and extent of buckle, number of cryo applications, type of surgery, and type of anaesthesia. The mean preoperative pupillary diameter for patients with treatment was 7.87 mm and for those not treated with flurbiprofen was 7.45 mm. The difference was not statistically significant by Student's t-test. The mean postoperative pupillary diameter for patients with treatment was 5.98 mm and for those not treated with flurbiprofen was 5.88 mm. The difference was not statistically significant by Student's t-test. Additionally, there was no statistical difference in the pupillary diameter between the two groups at any stage of the operative procedure [Table 1].
The mean change in pupillary diameter from the preoperative value at various steps of surgery was compared between the treatment and the control groups. There was no statistical difference between the two groups at any step of the surgical procedure.
The mean change in pupillary size at conclusion for patients treated with flurbiprofen was 1.88 mm compared to 1.57 mm for those not treated. This difference was not statistically significant by the Student's t-test [Table 2].
The amount of decrease in pupillary size for each step of the surgical procedure was calculated by subtracting that value from the previous step value. Overall, the mean pupillary decrease for conjunetival opening and muscle bridling was 0.25 mm, for localization and cryopexy it was 0.5 nom, for subretinal fluid drainage and temporary buckle placement it was 0.43 mm, and for permanent buckle, band tie and conjunctival closure it was 0.53 mm.
The mean change in pupil size of the study population was determined for a variety of subgroups. The mean pupil diameter change for patients less than 45 years was 1.59 and for those 45 years and older was 1.83 mm. In phakic eyes, the mean pupil change was 1.84 mm and in aphakic it was 1.58 mm. The pupil decreased in size with an average of 1.68 mm in surgery lasting less than 2 1/2 hours and 1.74 mm in surgery lasting longer than 2 1/2 hours. Eyes which received less than 10 cryo applications had a pupillary decrease of 1.58 mm compared to 1.82 mm in eyes with more than 10 applications of cryopexy. For eyes that received 7 mm size buckle, the decrease in pupillary size was 1.47 mm and for larger sized buckles, the decrease was 1.90 mm. The mean pupil change for eyes with buckle extending less than or equal to 2 quadrants was 1.47 mm as compared to 1.98 mm for eyes that had buckling for more than 2 quadrants. The study population was further divided into treatment and control groups for statistical analysis and the mean pupillary decrease was similarly calculated for the treated and untreated eyes in the same subgroups as above.
The effect of preoperative treatment with flurbiprofen was assessed by Student's t-test between the treatment and control groups. In none of the subgroups was the mean change in pupillary size found to be significantly different between the treatment and control populations [Table 3].
The pairs of subgroups were analysed among themselves both in the treatment population and in the control population by paired t-test. Both in the treatment group [Table 4] and the control group [Table 5] there was no difference between these subgroups.
A small pupil can severely limit scleral buckling surgery. Hence, it is imperative that a dilated pupil obtained preoperatively by routine dilatation drops be maintained till the conclusion of surgery.
Intraoperative miosis can occur by either inflammatory or neural mechanism. The inflammatory mechanism leading to intraoperative miosis are thought to be related to the prostaglandin system.  Pros tagland ins which are present in eyes and can be synthesised by ocular tissues  are derived from arachidonic acid via the enzyme cyclo-oxygenase.  They have been identified in aqueous humour after alkali burn, ocular trauma, ocular surgery, and iris massage during intraocular manipulation. Apart from other inflammatory effects, they have been shown to induce miosis in experimental animal studies. , it is therefore logical to surmise that prostaglandin inhibitors should be able to prevent surgery-induced miosis. 
Flurbiprofen is a phenylakanoic derivative that inhibits cyclo-oxygenase and thereby diminishes prostaglandin synthesis.  Pharmacokinetics of this drug have been well studied" and it has been shown to suppress the blood-aqueous barrier breakdown and ocular inflammation.  More importantly, it prevents surgically induced miosis in experimental animals' and during cataract surgery. 
Neural mechanisms such as decreased anaesthetic effect or direct stimulation of long posterior ciliary nerves can also cause intraoperative miosis.  Thoughit is known that substance P is released in response to nerve stimulation and it causes miosis when injected intracamerally sub its role in surgery-induced miosis is yet to be elucidated.
We found a mean decrease of 1.88 mm in patients treated with flurbiprofen as compared to 1.57 mm in those not treated. This difference was not statistically significant. Additionally, we have demonstrated the ineffectiveness of flurbiprofen at all steps of the surgery. We also found that older age group, phakic eyes, longer duration of surgery, increased number of cryo applications, larger size and extent of the buckle were associated with a greater decrease in mean pupillary size, but it did not reach statistical significance.
Two earlier studies have shown the ineffectiveness of flurbiprofen in preventing intraoperative miosis in vitreo-retinal surgeries. , While these studies have shown no beneficial effect of flurbiprofen in maintaining pupillary dilatation during scleral buckling surgery, our study additionally shows ineffectiveness of the drug at all stages of the surgery in preventing intraoperative miosis. We also found that application of flurbiprofen caused a larger miosis in flurbiprofentreated patients than in those not receiving flurbiprofen. This was also observed in an earlier study. All studies that show prevention of miosis with flurbiprofen use are related to anterior segment surgeries where the tissue trauma is minimal and surgery is for a short duration. Scleral buckling procedures are of a much longer duration than routine cataract surgery. Additionally, in scleral buckling, greater tissue trauma and manipulation is involved. Furthermore, it is known that cryo application and drainage of subretinal fluid cause hypotony which leads to miosis. Cryopexy also induces an inflammatory response and breakdown of blood-retinal barriers,  causing release of prostaglandins. The other factor that might be operative is the placement of scleral buckle which presses on the long ciliary nerves causing an increased neural input for miosis.  In the study that examined the role of the drug on inflammation following cyclocryotherapy, the effect of flurbiprofen was seen only 7 to 8 weeks after the procedure and the authors concluded that the inflammation was too great to control with topical therapy. We too feel that the inhibitory effect on miosis by flurbiprofen is overpowered by the strong inflammatory input associated with scleral buckling surgery.
Our study has demonstrated the ineffectiveness of flurbiprofen on maintaining mydriasis at all steps of the surgery and we do not recommend the use of flurbiprofen for preventing miosis in routine scleral buckling operations. Our study was limited by the small number of patients recruited and may be this discrepancy can be avoided by using a larger sample size than our present study.
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