Year : 2003 | Volume
: 51 | Issue : 1 | Page : 45--52
The incidence of vitreous loss and visual outcome in patients undergoing cataract surgery in a teaching hospital.
M Kothari, R Thomas, R Parikh, A Braganza, T Kuriakose, J Muliyil
Department of Ophthalmology, Schell Eye Hospital, Christian Medical College, Vellore, India
Department of Ophthalmology, Schell Eye Hospital, Christian Medical College, Vellore
Purpose: To determine the incidence of vitreous loss in patients undergoing cataract surgery and the visual outcome in a tertiary teaching hospital.
Methods: Hospital records of 2095 consecutive patients undergoing cataract surgery between July 1999 and June 2000 were reviewed in this non-concurrent cohort study. Incidence and visual outcome of vitreous loss managed using standard vitrectomy techniques were assessed for different cataract surgical techniques (extracapsular, Blumenthal technique and phacoemulsification) as well as at different levels of surgical training. The outcome was compared with matched cases without vitreous loss (controls).
Results: Vitreous loss occurred in 160 of 2095 eyes (7.63%; CI -7 to 9.3): 8.3% for ECCE, 8.1% for the Blumenthal technique and 5% with phacoemulsification. Vision ž 6/18 was achieved in 85% of cases and 95% of controls. For experienced surgeons, 95% of the cases and controls had vision ž 6/18. 5.8 % of cases and 0.7% of controls had vision < 6/60. One patient in each group was blind following cataract surgery; both had operable cataracts in the fellow eye.
Conclusions: The vitreous loss rate in this tertiary teaching hospital is relatively high. This complication, managed with standard surgical techniques, is compatible with good visual outcome. In eyes with vitreous loss, the final visual acuity achieved by experienced surgeons was similar to that in uncomplicated cases.
|How to cite this article:|
Kothari M, Thomas R, Parikh R, Braganza A, Kuriakose T, Muliyil J. The incidence of vitreous loss and visual outcome in patients undergoing cataract surgery in a teaching hospital. Indian J Ophthalmol 2003;51:45-52
|How to cite this URL:|
Kothari M, Thomas R, Parikh R, Braganza A, Kuriakose T, Muliyil J. The incidence of vitreous loss and visual outcome in patients undergoing cataract surgery in a teaching hospital. Indian J Ophthalmol [serial online] 2003 [cited 2020 Apr 7 ];51:45-52
Available from: http://www.ijo.in/text.asp?2003/51/1/45/14738
Despite great advances in surgical techniques of cataract extraction, we continue to face a multitude of complications that can compromise the results of cataract surgery. The most common and significant complication that can affect the final visual acuity in cataract surgery is vitreous loss. It is more frequent in a training program. In this otherwise uncomplicated surgery, the incidence of vitreous loss has been variably reported as 0% - 19.,, Jaffe has proposed that an acceptable figure would be less than 3%. An National Program for Control of Blindness (NPCB) survey showed that vitreous loss was the commonest complication of cataract surgery, amounting to in 6% of cases.
The World Health Organization (WHO) guidelines for reasonable quality of visual outcome after cataract surgery state that 80% of patients should have presenting visual acuity of 6/18 or better, and including preexisting pathology, less than 5% should have an presenting visual acuity of . Smith and Seiff reported vitreous loss in residency training at various level of experience. Vitreous loss occurred in 16% of eyes operated on by first-year residents, in 10% of eyes operated on by second-year residents, and in 6% of eyes operated on by third-year residents. Allinson reported 14.7 % vitreous loss in cases operated by third-year residents learning phacoemulsi-fication. Davitt and Cohen found that of 184 surgeries handled by residents learning temporal clear corneal phacoemulsification, 14 % had posterior capsular rupture and 11 % had vitreous loss. Best corrected visual acuity of 6/12 or more could be achieved in 86 %.
The purpose of our study was to determine the overall vitreous loss rate and determine the final visual outcome of cataract operations complicated by vitreous loss and managed by standard microsurgical techniques in a tertiary care training center in India.
Materials and Methods
The study population was identified from the operating room register and the medical record of each patient was retrieved from the medical records department (MRD). The surgical details were obtained from the cataract surgery data sheet and operation notes. Details of the postoperative period and follow-up were abstracted from the patient's record.
Inclusion criteria for cases with vitreous loss were as follows: patients of either gender, age 40 years or more, undergoing routine cataract surgery; age-related or steroid induced cataracts; and cataract surgery performed by residents or members of the faculty of the institution.
Exclusion criteria for cases of vitreous loss were as follows: posterior capsular rupture without vitreous loss; traumatic or complicated cataract; preoperative morbidity that could account for poor visual outcome (these patients contributed to the vitreous loss rate but were excluded from the visual outcome data); and lens-induced glaucoma and cataract associated with glaucoma.
Each case of vitreous loss was individually matched for age ± 5 years; gender; technique of cataract surgery (ECCE/ Blumenthal/Phacoemulsification) and surgeon. Similar inclusion and exclusion criteria were applied. Surgeon matching was done by applying the above matched variables to the population of cataract surgery patients operated upon by the same surgeon on his or her operating day nearest to the day on which the case with vitreous loss occurred. In those few cases where a suitable control could not be obtained, we used a control matched in a similar way with a surgeon who had the same level of experience.
The WHO guidelines state that at least 80 % patients should achieve best-corrected visual acuity of 6/18 or more. We assumed that in uncomplicated cases 90 % of patients would achieve a visual acuity of 6/18 or more. Assuming a 10 % difference in visual outcome between the two groups, we calculated the sample size using the following formula:
N = 2x (p1q1) + (p2q2) x (Za XZβ )
p1 = Proportion of interest (visual acuity ž 6/18) in patients without vitreous loss = 90%
p2 = Proportion of interest (visual acuity ž 6/18) in patients with vitreous loss = 80 %
q1 = 100-p1, q2 = 100-p2
Za =1.96, a = 0.05
Z β =0.84, b = 0.2
N = 140. Each group comhrised 140 patients.
Retrobulbar or peribulbar anaesthesia was used for all patients. The technique used for a standard ECCE was as described in standard texts. The modified Blumenthal's technique we use has been described. Phacoemulsification was performed by the four-quadrant divide-and-conquer method as described by Gimbel or by the stop-and-chop technique of Koch. , 
Vitreous loss was defined as prolapse or anterior displacement of the vitreous gel into the anterior chamber beyond the plane of the posterior capsule. Confirmation of vitreous loss mandated examination with an endoilluminator. If vitreous prolapse was not present, the surgery was continued as planned.
Management of vitreous loss
Use of an endoilluminator was mandatory. All instruments were removed from the anterior chamber (AC); if an AC maintainer (ACM) was in use, the height of the infusion bottle was lowered immediately; the goal was to provide the minimum infusion required to keep the chamber formed and perform a "closed" anterior vitrectomy. The nucleus, epinucleus and cortex were managed appropriately.
A mechanical vitrectomy instrument was introduced through a paracentesis and a partial anterior vitrectomy was performed. Irrigation was separated from the cutting. When in use (phacoemulsification and Blumenthal technique), the ACM provided the irrigation. For standard extracapsular surgery, a canula connected to a bottle of balanced salt solution (BSS) and introduced through the sutured wound was used for irrigation. The goal was to remove all vitreous from the anterior and posterior chambers and prevent any contact with the iris. As much of the capsule as possible was preserved.
The endoilluminator was used once again to confirm that the anterior chamber and posterior chambers had been adequately cleared of vitreous. An intraocular lens (IOL) of appropriate design was implanted either in the ciliary sulcus or in the anterior chamber depending on the amount of capsular support available for safe implantation. In order to ensure that there was no vitreous in the wound (or side ports), these incisions were swept with a nucleus spatula introduced from one of the side ports. After pupillary constriction with intracameral pilocarpine the endoillumi-nator was used for a final check to detect residual vitreous strands.
On the first postoperative day, the uncorrected and pinhole visual acuity were checked for all patients. The anterior segment was examined by slitlamp and applanation IOP was measured. Distant direct ophthalmoscopy was performed and the fundus was examined with a 90D lens on a slitlamp; an indirect ophthalmoscope was used when indicated.
Routine follow-up visits were planned at 1 week, 3 weeks and 6 weeks postoperatively. When required, inpatient hospital stay was prolonged and visits were made more frequent.At each visit the examination included refraction, IOP measurement, slitlamp and fundus check. Indirect ophthalmoscopy with depression and stereobiomicroscopic examination of the posterior pole was performed at 6 weeks. If the BCVA at any of the follow-up visits was not consistent with anterior segment findings, a dilated stereo biomicroscopic examination was performed at that time. All patients were maintained on topical corticosteroids and chloramphenicol eye drops three times a day till at least 6 weeks after surgery. Cycloplegics and nonsteroidal anti-inflammatory drugs (NSAIDs) were used as indicated. In patients with sulcus fixated IOLs and ACIOLs cycloplegics were not routine but were employed for posterior segment examination. Diagnosis of cystoid macular oedema (CME) was made when the BCVA was
In uncomplicated cases, there was minimal (if any) difference in outcomes between the levels of surgeons. The visual outcome in the control group for Level 1 and Level 2 surgeons was similar to that of Level 3 surgeons. More than 95% of patients achieved a visual acuity > 6/18 in uncomplicated surgery regardless of the surgeon's level of experience; there was no statistical or clinically significant difference here. It is only in the vitreous loss group that the surgeon's experience really makes a difference.
The literature suggests that even if managed well, vitreous loss is associated with higher morbidity and a poorer visual outcome than an uncomplicated case.,  It also leads to significantly longer hospitalisation for study patients compared to controls. In our patients the commonest identifiable cause for vision <6/18 after vitreous loss was cystoid macular oedema. The commonest cause was corneal decompensation should we consider vision less than 6/60 only. Of the 8 such patients in the study group, 5 had corneal decompensation, one had suprachoroidal haemorrhage, one had vitreous haemorrhage and one developed a macular scar. One patient in the control group also had postoperative visual acuity less than 6/60 and corneal decompensation. Greater corneal endothelial loss reportedly occurs in eyes concurrently treated with anterior vitrectomy and in eyes with ACIOL., In this study the BCVA was significantly greater in patients with vitreous loss who received a PC-IOL compared to those in whom an AC-IOL was implanted. This probably reflects the severity of the complication (and associated surgical manipulations) in cases that required an AC-IOL. Poor BCVA in the No-IOL group probably reflects this same trend, with poor visualisation leading to a decision to abort primary lens implantation.
The poor outcome following vitrectomy in inexperienced hands (mainly due to corneal causes) suggests that teaching needs improvement. The extra manipulations in a case with vitreous loss compounded by unskilled hands performing vitrectomy, is probably the cause for the poor outcome. We teach management of vitreous loss in the same stepwise manner that we teach cataract surgery. Currently, however, we do not take over the case unless considered absolutely necessary. Our threshold for taking over the management should be lower. If a decision is made to implant an IOL in this scenario, it may be safer for the senior surgeon to perform this step. Naturally, such decisions will need to be individualized.
In summary, vitreous loss in our teaching hospital is high, but similar to that reported in the literature for surgeons-in-training. Differences in rates can partly be explained by differences in definitions and methods of ascertainment. Vitreous loss does lead to a poorer outcome compared to an uncomplicated cataract operation. However, appropriately managed cases do obtain good vision. Part of the poor visual outcomes of cataract surgery reported nationally could be due to lack of recognition or inappropriate management of vitreous loss. If outcomes are to be improved, mechanized anterior vitrectomy instruments should be made available at all cataract surgical sites and surgeons must be trained in their use. Any surgeon performing cataract surgery should be well versed with the management of this complication.
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