Prognostic Factors for Low Visual Acuity after Cataract Surgery with Vitreous Loss: Study
The frequency of vitreous loss during cataract surgery using phacoemulsification techniques ranges from 1.1% to 5%. Risk factors for posterior capsular rupture that may lead to vitreous loss include small pupil, previous ocular trauma, pseudoexfoliation (PXF), poor visualization secondary to corneal opacities, corneal transplantation, postradial keratotomy, dense/mature cataract, zonular weakness, lack of patient cooperation, posterior polar cataract, postvitrectomy, and inherited conditions such as Marfan's syndrome and deep or shallow anterior chamber.
Intraoperative signs for posterior capsule rapture with vitreous loss may include sudden deepening of the anterior chamber, transitory appearance of a clear red reflex peripherally, inability to rotate a previously mobile nucleus, difficulty in burying the phaco needle into the nucleus, and tipping of one pole of the nucleus. Vitreous loss can be associated with an adverse functional outcome secondary to either cystoid macular edema, corneal decompensation, glaucoma, endophthalmitis, or a combination thereof. It is not clear what variables may impact the final postoperative acuity following this complication.
Michael Mimouni and team carried out a study with aim to try and determine what factors are associated with a low visual acuity in patients experiencing vitreous loss during cataract surgery.
This was a retrospective, noncomparative, interventional, case study of patients experiencing vitreous loss during cataract surgery. Data collected included demographics, best corrected visual acuity (BCVA), axial length (AL), presence of ocular comorbidity affecting central vision, timing of intraocular lens (IOL) implantation, position of the implanted lens, and the presence of corneal sutures. Low visual outcome was defined as BCVA< 20/40.
- Overall, 179 cases of vitreous loss during cataract surgery using phacoemulsification were identified. Mean age and axial length were 73 ± 12 years and 23.5 ± 1.3 mm.
- Risk factors for capsular rupture were identified in 30% with the most common being dense/mature cataract. Additional factors were narrow pupils, pseudoexfoliation glaucoma, zonular weakness, posterior polar cataract, and lack of patient cooperation.
- Age, sex, BCVA, and axial length were not found to have significant associations with low visual outcome (P ≥ 0.05).
- Ocular comorbidity was the only preoperative parameter significantly associated with low visual outcome in univariate analysis. Ocular comorbidity was present in 36%. Patients undergoing cataract surgery with additional pathologies were 4 times more likely to have low visual outcome.
- There was no significant association between specific comorbidities (glaucoma, AMD, and proliferative diabetic retinopathy) and low visual outcome.
- Secondary IOL implantation and the use of corneal sutures during surgery were associated with a low visual outcome.
- Postoperative CME (7.9%) increased the risk for low visual outcome by nearly 3 times (P = 0.034). Other complications included increased intraocular pressure, mild ERM, and retinal detachment.
- Overall, 22 eyes required additional surgery. Reasons included retained lens material (n =14), IOL repositioning (n = 4), anterior vitrectomy (n = 3), and iris prolapse (n = 1).
Preoperative ocular comorbidity, secondary IOL implantation and type of implanted lens, corneal sutures, secondary PPV, CME, and other surgical complications were included as predictors of low visual outcome. Preoperative ocular comorbidity, secondary IOL implantation, CME, and other surgical complications were associated with low visual outcome in multivariate analysis.
Surgically demanding cases are at increased risk for capsular rupture. These include small pupils, dense/mature cataract, instillation of trypan blue, and loose zonules with or without pseudoexfoliation.
In the case of a posterior capsular rupture with vitreous loss, the IOL can be placed in front of the anterior capsule if the rhexis is round and the rim is adequate in size. But if the support is less than adequate, it may be necessary to place an anterior chamber IOL, iris fixated IOL, or scleral fixated IOL. In this study, a secondary IOL implantation was associated with worse visual outcomes (OR = 10.36, P =0.009). Authors speculated that this may stem from two different causes. One, cases where an IOL was not implanted during primary surgery were probably more complicated to begin with than those in which an IOL was implanted. Two, it may be that additional surgery may expose the eye to further complications which can be avoided if the IOL is implanted during primary surgery.
This study recognizes ocular comorbidity, secondary IOL implantation, and subsequent postoperative CME as risk factors for low visual outcome in patients experiencing vitreous loss during cataract surgery. However, most patients with this complication do have good outcomes, especially if no comorbidities are present at the time of surgery. Similarly, patients requiring PPV for retained lens material can have good visual results although the timing of this additional intervention is not defined. Ophthalmologists, specifically cataract surgeons, should be aware of these findings in order to give their patients more accurate prognosis.
Source: Michael Mimouni, Michal Schaap-Fogler, Philip Polkinghorne, Gilad Rabina and Rita Ehrlich; Hindawi Journal of Ophthalmology Volume 2021