|Year : 2017 | Volume
| Issue : 3 | Page : 143-148
Results of pupil dilatation using Oasis ring in eyes with narrow pupil during phacoemulsification
Ahmed M Ghoneim, Tamer E Wasfy
Ophthalmology Department, Tanta University Hospital, Tanta, Egypt
|Date of Submission||15-Feb-2017|
|Date of Acceptance||23-Jun-2017|
|Date of Web Publication||17-Oct-2017|
Ahmed M Ghoneim
Ophthalmology Department, Tanta University Hospital, 71 El-Bahr St, PO Box 4111, Tanta, Gharbia Governorate
Source of Support: None, Conflict of Interest: None
Purpose To compare the results using Oasis ring for mechanical dilatation of the pupil during phacoemulsification in cases of narrow pupil with nonmechanical dilatation.
Patients and methods This study included 80 eyes of 67 patients with cataract with narrow pupil. They were divided into two groups, each including 40 eyes. In one group, Oasis ring was used to achieve adequate pupillary dilatation, whereas in the other group, nonmechanical device methods such as bimanual stretching with partial sphincterotomies were used. Both groups were compared regarding achieved pupil size, additional time for dilatation, intraoperative difficulties, and postoperative pupil characters at 1-month follow-up.
Results The mean pupil size was 6.00±0.00 mm in the Oasis ring group, whereas it was 4.26±0.48 mm in the nonmechanical device dilatation group, with statistically significant difference. Additional intraoperative time needed for pupil dilatation was significantly longer in Oasis ring group where it ranged from 83 to 117 s, whereas in the nonmechanical device dilatation group, it ranged from 48 to 76 s. There was more liability for intraoperative difficulties as iris prolapse, minimal bleeding, and iris trauma in the nonmechanical device dilatation group. Postoperative pupil characters after 1 month were rounded, central, and reactive in the Oasis ring group with oval-shaped pupil found only in one (2.5%) eye and minute tears in two (5%) eyes, whereas oval pupil was found in seven (17.5%) eyes and minute tears in five (12.5%) eyes in the nonmechanical device dilatation group. Statistically significant differences were found between the two studied groups.
Conclusion Pupil dilatation with Oasis ring increases the intraoperative additional time for pupil dilatation, but it provides stable and sufficiently dilated pupil, with less liability for intraoperative complications when compared with non-mechanical device dilatation methods.
Keywords: narrow pupil, Oasis ring, phacoemulsification, stretch pupilloplasty
|How to cite this article:|
Ghoneim AM, Wasfy TE. Results of pupil dilatation using Oasis ring in eyes with narrow pupil during phacoemulsification. Delta J Ophthalmol 2017;18:143-8
|How to cite this URL:|
Ghoneim AM, Wasfy TE. Results of pupil dilatation using Oasis ring in eyes with narrow pupil during phacoemulsification. Delta J Ophthalmol [serial online] 2017 [cited 2021 Oct 16];18:143-8. Available from: http://www.djo.eg.net/text.asp?2017/18/3/143/216918
| Introduction|| |
Phacoemulsification has become a gold standard of cataract surgery. This procedure in eyes with a narrow pupil that do not respond to standard preoperative pharmacological management is a challenge for any ophthalmic surgeon .
A 5.5 mm or larger pupil allows the use of divide and conquer or other phacoemulsification techniques and a capsulorhexis of 4.0–5.0 mm could also be performed .
Poorly dilated pupil is one of the most common problems faced by cataract surgeons and is associated with a higher incidence of intraoperative complications such as capsular rupture and vitreous loss .
There are many causes of poor pupil dilatation, for example, diabetes mellitus, senile miosis, intraoperative floppy iris syndrome, pseudoexfoliation syndrome, uveitis with posterior synechiae, and some conditions after ocular surgery .
The goal of managing miotic pupils is to achieve adequate pupil size during surgery to perform phacoemulsification while still maintaining pupillary reactivity, near-normal pupil contour, and excellent visual results .
Several methods have been developed for enlarging miotic pupils during phacoemulsification including iris retractors, multiple sphincterotomies, and pupil stretch techniques . Several types of iris retractors and devices are available to manage small pupils. A simple popular method involves using iris hooks to stretch the pupil at different meridians until reaching adequate size. Another alternative is the disposable Malyugen pupil expansion device which is a foldable square made of 5-0 polypropylene with a coiled scroll at each of four corners. Oasis iris expander is a device used for insufficiently dilated pupils during ophthalmic surgery and sustaining visibility throughout the procedure. It is a molded polypropylene ring that has four pockets that cradle the delicate ocular tissue without potential tearing. Once the expander is removed, the iris returns to its normal shape and function ,,,,,,.
Healon GV (sodium hyaluronate 1.4%; Abbott Laboratories Inc., Abbott Park, Illinois, USA) is a highly viscous agent that adds expansion power to the pupil and maintains its size .
Multiple partial sphincterotomies with good postoperative function had been reported. Care must be taken to avoid totally transecting the iris sphincter ,.
In the present study, a new disposable Oasis ring iris expander device (Oasis; Oasis Medical Inc., Glendora, California, USA) was evaluated in a series of patients with narrow pupil during phacoemulsification.
| Patients and methods|| |
This is a prospective randomized study. It was carried out at the Ophthalmology Department, Tanta University Hospital, Egypt, in the period from October 2013 to September 2016. Informed consent was obtained from every participant in this study, and the ethical committee’s approval was obtained.
The study included 80 eyes of 67 patients prepared for cataract removal by phacoemulsification in which adequate pupil dilatation (>3.5 mm) could not be achieved pharmacologically either preoperatively or intraoperatively and so narrow pupil was considered.
Pharmacologically dilated pupils (>3.5 mm) either preoperative or intraoperative with viscodilatation by Healon GV (viscomydriasis), and patients contraindicated to phacoemulsification and previous cyclodestructive interventions were excluded from the study.
The preoperative pharmacologic regimen used in these 80 eyes included the use of phenylephrine 2.5% eye drops (phenylephrine hydrochloride ophthalmic solution USP 2.5%; Paragon Biotech Inc., Portland, USA), tropicamide 1% eye drops (Mydriacyl; Alcon Laboratories Inc., Fort Worth, Texas, USA), and cyclopentolate 1% eye drops (Colircusi Cicloplejico; Alcon Cusi S.A., Barcelona, Spain). The eye drops were instilled three times at 10-min intervals starting 1 h before surgery. Nepafenac 0.1% eye drops (Nevanac; Alcon Laboratories Inc.) were also administered four times daily starting 1 day before surgery.
Intraoperatively, Healon GV (sodium hyaluronate 1% or 1.4%; Abbott Laboratories Inc.) was used to achieve adequate dilatation. Intraoperative pupil size was measured by surgical caliber horizontally and vertically after this step.
The eyes were divided into two groups:
- Overall, 40 eyes with narrow pupil (nonmechanical device dilatation group) were dilated without using internal device. They were dilated with bimanual pupil stretching using hooks (stretch pupilloplasty) and partial sphincterotomies using Vannas spring scissors (nonpupil expander group) ([Figure 1]a and [Figure 1]b).
|Figure 1 (a & b) Showing mechanical stretching of the pupil (stretch pupiloplasty).|
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- Moreover, 40 eyes with narrow pupil (mechanical device dilatation group) were dilated using Oasis ring iris expander of size 6.25 mm (Oasis; Oasis Medical Inc.) (pupil expander group) ([Figure 2]a–[Figure 2]c and [Figure 3]a–[Figure 3]j).
|Figure 2 (a) Showing the platform containing unfolded Oasis ring, (b) Showing Oasis ring dilating the pupil and (c) Showing removal of Oasis ring at the end of the procedure.|
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|Figure 3 (a) Showing the preoperative narrow pupil. (b–e) Showing steps of inserting Oasis ring to dilate the pupil. (f) Showing phaco tip & chopper during removal of cataractous lens with Oasis ring in place. (g) Showing fully dilated pupil after removal of cataract with rhexis edge. (h & I) Showing steps for removal of Oasis Ring after implanting the IOL. (j) Showing pupil rounded at the end of the procedure.|
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All patients underwent standard phacoemulsification by the same surgeon (A.Gh.) through a 2.8-mm superior temporal clear corneal incision with a foldable intraocular lens implantation.
Follow-up of all cases was done after 1 month to evaluate the characters of the pupil regarding shape, position, reactivity to light, and presence of iris trauma.
Statistical presentation and analysis of the data of the present study were conducted using the mean, SD, χ2, and t-test by SPSS V.20 (IBM Corporation, Armonk, New York, USA).
| Results|| |
The study included 80 eyes of 67 patients with narrow pupil owing to various causes. The right eye was operated in 53 cases and the left eye in 27 cases. The age of the patients ranged from 47 to 73 years in the mechanical device dilatation group, with a mean of 64.8±8.2 years, whereas it ranged from 52 to 78 years in the nonmechanical device dilatation group, with a mean of 59.9±9.3 years. The mechanical device dilatation group included 21 male patients and 13 female patients (six bilateral cases) whereas the nonmechanical device dilatation group included 16 male patients and 17 female patients (seven bilateral cases).
Regarding the causes of narrow pupil, many causes were encountered in the present study, including diabetes mellitus, age related (senile miosis), uveitis, pseudoexfoliation syndrome, intraoperative floppy iris syndrome, and long-term pilocarpine use. Diabetes mellitus was the most common cause, which was encountered in 42 (52.5%) eyes ([Table 1]).
Intraoperative pupil size was measured by surgical caliber horizontally and vertically before dilatation. In the mechanical device dilatation group, the mean pupil size was 2.75±0.08 mm and in the nonmechanical device dilatation group, the mean pupil size was 2.74±0.32 mm (P=0.924 with insignificant difference). After dilatation, the size of the pupil changed from a mean of 2.75±0.08 mm to a mean of 6.00±0.00 mm in the mechanical device dilatation group, whereas in the nonmechanical device dilatation group, the increase in pupil size was from a mean of 2.74±0.32 mm to a mean of 4.26±0.48 mm, with statistically significant difference between the two studied groups (P<0.001) ([Table 2]).
Additional intraoperative time for pupil dilatation was calculated and found ranging from 83 to 117 s with a mean of 93.2±11.36 s in the mechanical device dilatation group, whereas it ranged from 48 to 76 s with a mean of 54.6±9.88 s in the nonmechanical device dilatation group (P<0.001). Additional one corneal incision was needed to introduce the dilatation hooks to stretch the pupil in cases of nonmechanical device group whereas no additional incision was needed in the mechanical device dilatation group ([Table 2]).
The intraoperative difficulties encountered in the mechanical device dilatation group were minimal bleeding in two (5%) eyes and mild iridodialysis in one (2.5%) eye. In the nonmechanical device dilatation group, there was iris prolapse in three (7.5%) eyes, bleeding in four (10%) eyes, iris inclusion by the phacoemulsification probe in three (7.5%) eyes, and iris trauma during irrigation aspiration in two (5%) eyes. Statistically significant difference was found between the two studied groups, with P value less than 0.001 ([Table 3]).
The removal of Oasis ring after intraocular lens implantation at the end of surgery was easy and successful without complications in all cases (100%).
During follow-up 1-month postoperatively, the pupil characters showed that pupils dilated using Oasis ring (mechanical device dilatation group) were central and rounded in shape in 39 (97.5%) eyes and reactive in 39 (97.5%) eyes; the remaining one (2.5%) eye was oval shaped with less reactivity, whereas minute tears were found in two (5%) eyes. On the contrary, in the nonmechanical device dilatation group, the pupil was decentered and oval in shape in seven (17.5%) eyes. In addition, less reactive pupil was found in nine (22.5%) eyes and minute tears were found in five (12.5%) eyes. Regarding postoperative characters of the pupil, statistically significant difference was found between the two studied groups (with P<0.001) ([Table 4]).
| Discussion|| |
The development of surgical techniques in modern ophthalmology is connected with the reduction of surgical trauma. Phacoemulsification in eyes with a narrow pupil not responding to standard preoperative pharmacologic management is known to be a challenge for any ophthalmic surgeon. During phacoemulsification, it is necessary to have a good trans-pupillary access to the lens .
A small pupil may cause damage to the patient’s eye by emulsification of the iris or may cause complications such as sphincteric tears, intraoperative bleeding, zonular dialysis, posterior capsular tear, or nucleus drop. Prolonged surgical time and increased maneuvering may result in postoperative complications such as striate keratopathy, uveitis, secondary glaucoma, irregular pupil, endophthalmitis, and cystoid macular edema in addition to floppy, torn, or atrophic iris, which result in suboptimal surgical outcome and an unsatisfied patient .
The ability of the pupil to dilate well should be determined in the outpatient clinic during the preoperative visit. Both topical cycloplegic mydriatics and sympathomimetic agents should be administered to assess dilatation of the pupil. Pharmacological dilatation might break posterior synechiae preoperatively. Even if adequate pupil dilatation is not achieved by this preoperative office regimen, it allows the surgeon to plan an intraoperative pupil management strategy .
Akman et al.  documented that bimanual stretching achieved good pupil size (4.9±0.7 mm), but the size was usually smaller than that obtained by other systems in their study. Bimanual stretching could be performed in less than 1 min (55±10 s) and was thus a time-saving method but could cause microruptures of the sphincter that were functionally insignificant . Similar results were obtained in the present study.Comparable results to those found in the current study were obtained by Vasavada and Singh  who used Healon GV to dilate narrow pupil. A 4.42±0.58 mm pupil was achieved. Iris was traumatized in 10 (33%) eyes of their study during subincisional cortex removal. Blind manipulations under the pupil increase the chances of catching the iris. Although they had successfully used this technique for small pupil in compromised eyes, they admitted that in certain situations (e.g. inability to perform a capsulorhexis larger than the pupil size, possible hidden small chips of hard nuclei, doubtful cortical cleanup, uncertainty of in-the-bag haptic placement, and suspicion of zonular dialysis), pupil widening devices such as flexible iris retractors may be considered .
To the best of our knowledge, no previous reports about using Oasis ring are available. Oasis ring in the present study resulted in increasing the pupil size from a mean of 2.75±0.08 mm to a mean of 6.00±0.00 mm. Insertion of Oasis ring needed additional intraoperative time of 93.2±11.36 s to achieve pupil dilatation. No additional corneal incision was needed more than usual. Postoperative pupils during follow-up period were central, rounded, and reactive.
| Conclusion|| |
Pupil dilatation with Oasis ring increases the intraoperative additional time for pupil dilatation, but it provides stable and sufficiently dilated pupil, with less liability for intraoperative complications and preservation of pupil characters when compared with the nonmechanical device dilatation method.
The work was accomplished in Tanta University Hospital.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]