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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 57  |  Issue : 1  |  Page : 17-20

Outcomes of phacoemulsification in previously vitrectomized eyes


1 Department of Cornea and Refractive Services, Aravind Eye Hospital, Madurai, Tamil Nadu, India
2 Department of Cataract and IOL Services, Aravind Eye Hospital, Madurai, Tamil Nadu, India

Date of Web Publication10-Jun-2019

Correspondence Address:
Dr. Madhu Shekhar
Aravind Eye Hospital, Madurai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/tjosr.tjosr_2_19

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  Abstract 


Aim: To describe and determine the intraoperative and postoperative complications stemming from technical difficulties and anatomical aspects of patients undergoing phacoemulsification after pars plana vitrectomy (PPV). Materials and Methods: In this prospective study, thirty individual eyes who presented with cataract in a previously vitrectomized eye were analyzed. The indications for PPV, operative details of PPV, and postoperative complications were noted. The best-corrected visual acuity after vitrectomy, type of lens opacity that developed following PPV, visual acuity immediately prior to cataract surgery, duration between PPV and subsequent cataract extraction, estimated intraocular lens (IOL) power, formula used for calculating the IOL power, IOL type, intraoperative complications, best final visual acuity following phacoemulsification, and finally the incidence of neodymium-doped yttrium aluminum garnet capsulotomy were noted. Statistical Analysis: SPSS for Windows, version 11.0.1, and Microsoft Excel 2007 were used. Chi-square test was used to compare complication rates. Results: Overall 86% of the eyes had improved visual acuity post cataract surgery, 11% remained the same, and 3% of it worsened. Intraoperatively, small pupil, deepening of the anterior chamber, bowing of iris–lens diaphragm, difficulty in capsulorrhexis, and presence of posterior-capsular plaque were noted. Posterior-capsule opacification was the most common late postoperative complication. Conclusion: Although challenging, with prior knowledge regarding vitrectomized eyes, such cases can be performed safely and complication rates are acceptably low.

Keywords: Pars plana vitrectomy, phacoemulsification, posterior-capsule opacification


How to cite this article:
Gandhi P, Radhakrishnan N, Shekhar M. Outcomes of phacoemulsification in previously vitrectomized eyes. TNOA J Ophthalmic Sci Res 2019;57:17-20

How to cite this URL:
Gandhi P, Radhakrishnan N, Shekhar M. Outcomes of phacoemulsification in previously vitrectomized eyes. TNOA J Ophthalmic Sci Res [serial online] 2019 [cited 2019 Jul 17];57:17-20. Available from: http://www.tnoajosr.com/text.asp?2019/57/1/17/259879




  Introduction Top


An increasing number of posterior-segment diseases are being treated successfully with pars plana vitrectomy (PPV) nowadays, and cataract management after vitrectomy has become an important factor in the visual rehabilitation of these patients. Cataract development in the phakic eye after PPV is common with rates of 17%–80%.[1],[2],[3],[4] A clear crystalline lens is preserved whenever possible during PPV; however, some cataract changes can occur in up to 88%[5],[6],[7],[8] of cases after vitrectomy. Thus, cataract extraction is becoming necessary with increasing frequency in vitrectomized eyes.

In addition to a progressive nuclear opacification, which may occur after any type of vitrectomy, transient feathering of the lens often occurs after intraocular gas tamponade, whereas permanent subcapsular opacification may occur in silicone oil-filled eyes. Nuclear opacification after vitrectomy, morphologically and histologically, resembles age-related cataracts but shows a faster progression. Lens touch following PPV is rare but not an uncommon complication. Speed of the development of cataract and any sign of posterior-capsule dehiscence on slit lamp following vitrectomy should be seen with a suspicion of lens touch.

Several authors have reported difficulties during cataract surgery after vitrectomy. They describe decrease in vitreous support of the lens, zonular weakness, an excessively mobile posterior capsule, positive posterior pressure, poor visibility due to silicon oil in the anterior chamber, and posterior-capsule plaque. A knowledge of the different types of cataract, their frequency, and cause may help develop strategies to prevent complications. Apart from intraoperative difficulties, intraocular lens (IOL) power calculation is a challenge in postvitrectomized eyes, and chances of postoperative refractive surprise are not uncommon. There are many studies available discussing the outcomes of extracapsular cataract extraction (ECCE) following PPV.[9],[10] Although those results are favorable, still, phacoemulsification cataract extraction has a definite edge as the intraoperative complications are well handled and managed because it is a closed-chamber technique.

It is also noted that, among the postoperative complications, posterior-capsule opacification is the most commonly encountered problem. Those complications occur in vitrectomized eyes earlier than that in nonvitrectomized eyes, and the need for neodymium-doped yttrium aluminum garnet (Nd-YAG) capsulotomy is also higher.

The objective of the study is to focus and determine the intra- and postoperative complications, stemming from technical difficulties, anatomical aspects, and intraoperative management of postvitrectomized patients who undergo phacoemulsification.

We report a prospective study of patients who underwent phacoemulsification after prior PPV.


  Materials and Methods Top


Study design

This prospective study of thirty individual eyes who presented to a tertiary hospital with cataract, in a previously vitrectomized eye, was conducted in the same hospital, during a period of 1 year.

Selection criteria

Inclusion criteria

  1. Patients who had undergone a successful, uneventful PPV surgery earlier with adequate documentation of the procedure
  2. Phakic after vitreous surgery
  3. Patients who had significant cataractous changes following PPV
  4. At least 6-month follow-up after cataract surgery.


Exclusion criteria

  1. Patients who had undergone multiple retinal procedures
  2. Inadequate documentation of the procedure
  3. Unsuccessful vitrectomy surgery
  4. Poor visual acuity following retinal surgery (<6/60)
  5. Patients who already had significant lens changes during the time of PPV
  6. Patients who had undergone any other ocular surgeries in the past (other than PPV).


Patients and methodology

All patients who were advised cataract extraction with planned phacoemulsification after PPV and satisfied the inclusion criteria were enrolled in the study. From the retina department case records, indications for PPV, operative details, and postoperative complications were noted. The best-corrected visual acuity (BCVA) after vitrectomy, type of lens opacity that developed following vitrectomy, visual acuity immediately prior to cataract surgery, duration between vitrectomy and development of cataract, estimated IOL power and formula used for calculating the IOL power, IOL type, intraoperative complications and observations, best final visual acuity following phacoemulsification, length of follow-up, status of posterior-capsule intraoperatively and postoperatively, and finally incidence of Nd-YAG capsulotomy were noted. The preoperative evaluation included a typing and gradient of the optical density of each cataract at the slit lamp in order to measure the extent to which PPV influenced the formation and progression of cataract.

Cataract surgeries were performed under retrobulbar anesthesia. A temporal clear corneal incision was made, and an infinity phacoemulsification machine with a mini flared 45°-angulated Kelman tip was used. Posterior-chamber IOL implantation was planned in all eyes. During surgery, hydroprocedure of the nucleus was done with great caution.

Statistical analysis

All data were entered in the master chart, and statistical methods were performed with SPSS for Windows, version 11.0.1, and Microsoft Excel 2007 (Redmond, Washington, USA). Statistical analysis was performed to compare age, postoperative visual acuity, and improvement in acuity. Chi-square test was used to compare the complication rates.


  Results Top


Thirty eyes of thirty patients who had prior PPV underwent phacoemulsification in the study period. The mean age of the patients was 65.3 ± 8.24 years. The male-to-female ratio was 23:7. Of the 30 eyes, 14 (46.6%) were right eyes and 16 (53.3%) were left eyes. The most common indication for PPV in our study group was proliferative diabetic retinopathy in 14 (46.6%) eyes, followed by retinal detachment in 8 (26.6%) eyes [Table 1]. Of the 30 study eyes, 22 had some (gas or oil) kind of tamponade used during the procedure (73.33%). Out of the 22 eyes, 19 had received silicone oil (86.36%) and 3 had expansile gas (13.63%). The mean time from vitrectomy to cataract surgery was 14.8 months, with the earliest presenting in 4.3 months and the last presenting in 20.2 months. Of the thirty patients, the uncorrected visual acuity was ≤5/60 in 4 (13.3%) eyes, 6/60–6/36 in 9 (30%) eyes, 6/24–6/12 in 12 (40%) eyes, and 6/9 or better in 4 (13.3%) eyes. Fourteen (46.6%) eyes had posterior subcapsular cataract and 13 (43.3%) eyes had nuclear sclerosis, with 3 (10%) eyes belonging to other types (2 posterior polar cataract and 1 mature cataract). The IOL power calculation was calculated using IOLMaster® (IOL Master 700, Carl Zeiss 73447 Oberkochen, Germany). For all eyes measuring more than 22 mm (19 eyes), SRK-T formula was used and for those eyes measuring <22 mm (11 eyes), Hoffer-Q formula was used. Both these formulae belong to the third generation of IOL formulae. For silicon oil-filled eyes, it was done in silicon oil-filled mode. All the patients underwent successful phacoemulsification with IOL implantation. The type of IOL used was predominantly single-piece hydrophobic acrylic foldable IOL (26 out of 30) and the rest had a three-piece foldable acrylic lens. The intraoperative characteristic findings are enumerated in [Table 2]. A significant number of patients (40%) had posterior-capsule plaque. The postoperative BCVA at 1-month postoperative period was 6/9 or better in 6 (20%) eyes, 6/12–6/24 in 14 (46.6%) eyes, 6/36–6/60 in 7 (23.3%) eyes, and 5/60 or worse in 3 (10%) eyes. The late postoperative problem encountered most frequently in our study was opacification of the posterior capsule. Twenty-one out of the 30 eyes (70%) had significant posterior-capsular opacification, of which 17 eyes underwent Nd-YAG capsulotomy before the end of the study. Despite the reported risks of retinal detachment after capsulotomy and the significant retinal pathology, retinal detachments or redetachments did not occur in any of our patients.
Table 1: Indications of pars plana vitrectomy

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Table 2: Intraoperative findings in patients during phacoemulsification

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  Discussion Top


Development of cataract following PPV in phakic eyes is common. Nonetheless, the accurate mechanism of the development of cataract has not been known. Old age; diabetes; operation time; the use of air, gas, or silicon oil within the eye; change of the permeability of the lens capsule caused by PPV; interference of anaerobic glycolysis; oxidation of lens proteins during surgery; and erroneous surgical techniques are thought to have an influence on the progression of cataract. Schachat et al.[7] reported that 17% of 128 phakic eyes developed cataract over a mean follow-up of 11 months. In our patients, cataract extraction was required 4 months to 20 months after the initial vitrectomy (mean: 14 months).

In most of the previous reports, nuclear sclerosis was the most common cataract type after vitrectomy.[11],[12],[13] Patients who had vitrectomy for macular hole, or epiretinal membrane, developed nuclear sclerosis. Overall, however, posterior subcapsular cataract (46.6%) developed in a slightly higher percentage of our study eyes compared to nuclear sclerosis (43.3%). The incidence of occurrence of other types of cataract was minimal (10%). In addition, we had more eyes with insertion of silicone oil and expansile gas during vitrectomy, which may account for the increased occurrence of posterior subcapsular cataract.

Weakened or loose zonules become apparent intraoperatively when phacodonesis or substantial posterior or lateral displacement of the lens occurred during the anterior capsulotomy. Thus, a capsulorrhexis forceps/a sharp cystitome was used to minimize tension on the zonules. In our study, 11 of the 30 eyes had insufficient mydriasis. Various options such as flexible iris retractors and iris sphincter stretching maneuver that uses a variety of hooks into preplaced paracentesis sites or placement of multiple iris sphincterotomies (or both) were employed to combat this problem.

In 1986, Sneed et al.[9] reported difficulties performing ECCE after vitrectomy. They noted that the anterior chamber was unusually deep, and they had difficulty in generating sufficient force to express the lens in the absence of vitreous. The deepening of the anterior chamber could not be modulated by the variation of the fluidic parameters of the phacoemulsification, lowering bottle height. Instrument that was useful, however, was substitution of a posteriorly angulated phaco tip. The use of this tip allowed successful engagement of the nucleus during posterior excursions as well as more efficient delivery of ultrasonic power to emulsify harder nuclei.

Zonular weakness requires gentle nucleus manipulation to avoid dehiscence. Flaccid posterior capsules are more prone to rupture during irrigation and aspiration. Cortical cleanup was remarkable for an excessively mobile posterior capsule that was prone to rapid anterior and posterior excursions when the irrigation was toggled between positions 0 and 1. When on irrigation alone, the posterior capsule would bow posteriorly. This excessive mobility of the iris–lens diaphragm in these vitrectomized eyes suggests that the compliance of the iris–lens diaphragm has changed. There are several explanations for this behavior. To begin with, the phakic vitrectomized eyes have a posterior segment that is primarily filled with fluid and does not contain the hyaluronic acid or collagen fibrils that confer the rheologic properties of a gel. As a result of this change, it provides less dampening effect for iris–lens movements. In addition, the vitreous base is attenuated and contains only a thin retrolenticular layer of vitreous. This thin layer of vitreous provides far less support to the lens during phacoemulsification than would the entire vitreous body. It is also noted that posterior-capsule plaque is a very common occurrence in previously vitrectomized eyes. Posterior-capsule plaques that are difficult to remove may be encountered. Primary posterior capsulorrhexis may be used to treat such plaques, but it was not done in our cases.

Our data show that cataract extraction in postvitrectomized eyes can be challenging. This appears to have a clinically significant difference compared with that of the currently expected cataract outcomes. The comparatively higher-than-expected rate of complications in our study group may reflect the higher-than-usual rate of comorbidities in this referral population.

The choice of IOL for postvitrectomized eyes is important. These eyes have a high potential for subsequent posterior-segment surgery. If there is any chance that silicone oil would be injected, it would be prudent to avoid the implantation of a foldable silicone IOL because silicone oil adheres irreversibly to silicone lenses, clouding the ocular media. Acrylic, polymethyl methacrylate, or heparin-coated IOLs are preferred.

Posterior-capsule opacification appears to be the most common postoperative complication in postvitrectomy cataract extraction eyes requiring Nd-YAG capsulotomy as a remedy.


  Conclusion Top


Posterior-capsule plaque was the most common, unique intraoperative finding. Posterior-capsule opacification requiring Nd-YAG capsulotomy was common in these patients, especially in those with silicone-filled eyes. Preexisting posterior-segment pathology limits the ultimate improvement in visual acuity, but substantial gains in visual acuity are realized by most patients. Phacoemulsification and IOL implantation can be performed safely after PPV and complications are acceptably low. Phacoemulsification in postvitrectomized eyes, although challenging, can be managed efficiently with the advent of newer phaco machines, by adjusting phaco parameters, and by prior knowledge regarding vitrectomized eyes. The speed of development of cataract and maturity of cataract soon after vitrectomy must be seen with a suspicion of lens touch and should be managed accordingly. Biometry should be done carefully in these cases, and the possibility of refractive surprise should be explained to these patients. Chances of intraoperative complications, need for postoperative Nd-YAG capsulotomy, and regular follow-up should be elucidated to the patients. Increase in the awareness of the possible intra-operative difficulties and the surgeons experience might have led to improved outcomes in these difficult situations.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Hutton WL, Pesicka GA, Fuller DG. Cataract extraction in the diabetic eye after vitrectomy. Am J Ophthalmol 1987;104:1-4.  Back to cited text no. 1
    
2.
Blankenship GW, Machemer R. Long-term diabetic vitrectomy results. Report of 10 year follow-up. Ophthalmology 1985;92:503-6.  Back to cited text no. 2
    
3.
Thompson JT, Glaser BM, Sjaarda RN, Murphy RP. Progression of nuclear sclerosis and long-term visual results of vitrectomy with transforming growth factor beta-2 for macular holes. Am J Ophthalmol 1995;119:48-54.  Back to cited text no. 3
    
4.
Melberg NS, Thomas MA. Nuclear sclerotic cataract after vitrectomy in patients younger than 50 years of age. Ophthalmology 1995;102:1466-71.  Back to cited text no. 4
    
5.
Blankenship G, Cortez R, Machemer R. The lens and pars plana vitrectomy for diabetic retinopathy complications. Arch Ophthalmol 1979;97:1263-7.  Back to cited text no. 5
    
6.
Rice TA, Michels RG, Maguire MG, Rice EF. The effect of lensectomy on the incidence of iris neovascularization and neovascular glaucoma after vitrectomy for diabetic retinopathy. Am J Ophthalmol 1983;95:1-11.  Back to cited text no. 6
    
7.
Schachat AP, Oyakawa RT, Michels RG, Rice TA. Complications of vitreous surgery for diabetic retinopathy. II. Postoperative complications. Ophthalmology 1983;90:522-30.  Back to cited text no. 7
    
8.
Blankenship GW. The lens influence on diabetic vitrectomy results. Report of a prospective randomized study. Arch Ophthalmol 1980;98:2196-8.  Back to cited text no. 8
    
9.
Sneed S, Parrish RK 2nd, Mandelbaum S, O'Grady G. Technical problems of extracapsular cataract extractions after vitrectomy. Arch Ophthalmol 1986;104:1126-7.  Back to cited text no. 9
    
10.
Smiddy WE, Stark WJ, Michels RG, Maumenee AE, Terry AC, Glaser BM, et al. Cataract extraction after vitrectomy. Ophthalmology 1987;94:483-7.  Back to cited text no. 10
    
11.
Nakazawa M, Kimizuka Y, Watabe T, Kato K, Watanabe H, Yamanobe S, et al. Visual outcome after vitrectomy for diabetic retinopathy. A five-year follow-up. Acta Ophthalmol (Copenh) 1993;71:219-23.  Back to cited text no. 11
    
12.
Fisk MJ, Cairns JD. Silicone oil insertion. A review of 127 consecutive cases. Aust N Z J Ophthalmol 1995;23:25-32.  Back to cited text no. 12
    
13.
Blankenship GW. Stability of pars plana vitrectomy results for diabetic retinopathy complications. A comparison of five-year and six-month postvitrectomy findings. Arch Ophthalmol 1981;99:1009-12.  Back to cited text no. 13
    



 
 
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