Intraoperative and postoperative complications of cataract surgery in eyes with pseudoexfoliation - An 8-year analysis.

INTRODUCTION: Pseudoexfoliation (PXM) is a fibrillar material deposited in the anterior chamber of the eye and can cause disintegration of zonules and make pupillary dilatation difficult. This can make surgery difficult and result in intraoperative and postoperative complications. The aim of this study was to learn about whether the presence of pseudoexfoliation caused significant complications during cataract surgery.
MATERIALS AND METHODS: We did a secondary data analysis of 12,992 eyes from 2007 to 2014 using the National Eye Database of Melaka Hospital Malaysia on intraoperative and postoperative cataract surgery complications of patients with PXM.
RESULTS: Patients with PXM were 2.68 times more likely to get intraoperative complications (P < 0.001). They had a higher incidence of lens subluxation, zonular dehiscence, and vitreous loss (P < 0.001). Although posterior capsule rupture (PCR) was the most common intraoperative complication during cataract surgery (4.8%), the presence of pseudoexfoliation was not associated with PCR (P > 0.05). We did not observe any association between patients with pseudoexfoliation and any of the postoperative complications such as corneal decompensation, raised intraocular pressure, and intraocular lens decentration (P > 0.05). Pseudoexfoliation did not cause corneal decompensation (P > 0.05) although corneal decompensation was the highest postoperative complication of cataract surgeries (0.18%).
CONCLUSIONS: Patients with PXM had a higher rate of intraoperative complications which were mainly vitreous loss and zonular dehiscence and also lens subluxation/dislocation. We observed poorer visual outcomes in those with PXM following cataract surgery. Patients with pseudoexfoliation should be identified and precautions taken to minimize these complications to get better visual outcomes. Copyright:

Introduction

Pseudoexfoliation (PXM) is a fibrillar material deposited in the anterior segment of the eye and poses a challenge to surgeons doing phacoemulsification. The material is commonly deposited in the anterior chamber, angle of the eye, iris, trabecular meshwork, anterior capsule of the lens, and also the cornea. Deposition of pseudoexfoliation on the zonular fibers and ciliary processes causes disintegration of the zonules. Infiltration of the pseudoexfoliative material on the iris stroma makes pupillary dilatation difficult. Pupils were smaller in eyes with PXM compared to those without PXM in a study of 1763 eyes undergoing cataract surgery on Spain (P < 0.001).[1]

Intraoperatively, there can be problems differentiating the anterior capsule from the pseudoexfoliative material. Tearing of the pseudoexfoliative material instead of the anterior capsule was reported in a 78-year-old white Woman.[2] Due to the weak zonules and small pupils, eyes with pseudoexfoliation have been associated with complications of zonular dehiscence, posterior capsule rupture (PCR), vitreous loss, and lens dislocation intraoperatively.[3]

Postoperatively, eyes with pseudoexfoliation are associated with increased aqueous flare and inflammation, raised intraocular pressure (IOP) resulting in glaucomatous damage, and corneal decompensation.[3] Postoperatively, in a study of 16 autopsied eyes with pseudoexfoliation, intraocular lens (IOL) decentration measurements ranged from 0.51 ± 0.35 (symmetrical fixation) to 0.61 ± 0.43 mm (asymmetrical fixation) showing a weak nonsignificant correlation of IOL decentration.[4]

Materials and Methods

We did a secondary data analysis on a sample size of 12,992 eyes of patients using the National Eye Database (NED) of Melaka Hospital Malaysia. We analyzed data covering an 8-year period from 2007 to 2014. Data were entered at 12 weeks postoperatively which was the period of follow-up unless complications arose, in which case patients were followed up for longer.

Permission to conduct the study was given by the Medical Research Ethics Committee and the study abided with the Declaration of Helsinki.

The NED is a service supported by the Ministry of Health (MOH). As an approach to collect health information, the NED is utilized by health-care workers.[5] By means of NED, the incidence, distribution, and risk factors of visually threatening eye diseases such as cataract, diabetic retinopathy, glaucoma, and contact lens-related corneal ulcer are evaluated along with the treatment outcomes. The information provided in the NED has come into great use in helping the MOH, nongovernmental organizations, private health-care providers, and industry in any program planning and evaluations that are focused on prevention and control of eye diseases, besides continuous improvement of ophthalmic service in the nation.

The Cataract Surgery Registry was initialized in 2002 to collect data on patients' demographic profile, type of cataract surgery performed and the outcome of the cataract surgery and complications.

Melaka is a state general hospital affiliated with Melaka-Manipal Medical College serving the population of Melaka. It serves as a referral hospital and is the only government hospital for cataract surgeries in the state. Due to free cost for civil servants and pensioners and cheaper cost for others, most patients opt for treatment here. The first report of the NED was made available in 2007.

First, we looked at the incidence of pseudoexfoliation among patients undergoing cataract surgeries in Melaka. All types of cataract techniques were included (phacoemulsification, extracapsular cataract extraction, and lens aspiration). We studied the prevalence based on age groups (<50, 50–59, 60–69, and 70 and above years), gender (male and female), and ethnicity (Malays, Chinese, Indians – which are the three main races of Malaysia and others).

For the purpose of analysis, we excluded preexisting associated comorbidities such as lens subluxation, zonular dehiscence, and poor vision due to noncataract pathologies such as retinopathies. Intraoperatively, we looked at the occurrence of zonular dehiscence, PCR, vitreous loss, and lens subluxation or dislocation. Next, we looked to see the incidence of postoperative complications such as raised IOP, the occurrence of corneal decompensation, and IOL decentration among patients with pseudoexfoliation.

Finally, we analyzed the visual outcome in patients with pseudoexfoliation. The visual outcome was taken as the best-corrected visual acuity (BCVA) based on refractions done by hospital-based optometrists and was taken at 12 weeks postoperatively. Visual acuity was classified as good vision (6/6–6/12), impaired vision (6/18–6/36), and poor vision (6/60 and worse).

We utilized Chi-square to obtain P values for analysis involving categorical exposure variables with categorical outcome variables. For each of these analyses, we obtained the odds ratio (OR) with 95% confidence interval (CI).

Results

12,992 patients, with or without pseudoexfoliation, who had cataract surgery done and completed 12-week follow-up were studied to analyze the intraoperative and postoperative complications. Of these 12,992 patients, 149 of them had findings of pseudoexfoliation.

Table 1 illustrates the demographic characteristics and occurrences of pseudoexfoliation among patients who had undergone cataract surgery. Patients with pseudoexfoliation were noted to be older with a mean difference of 6.2 years as compared to patients without pseudoexfoliation (P < 0.001). There was no significant difference in gender among patients with pseudoexfoliation with males accounting for 45.6% of these patients (P > 0.05). With regard to ethnicity, the Indian accounted for 36.9% of patients with pseudoexfoliation, whereas the Malays and Chinese contributed 36.2% and 23.4%, respectively. The Indians had a 4.99 times likelihood of being associated with pseudoexfoliation as compared to the Chinese (P < 0.001). However, there were no significant differences between other ethnic groups as compared to the Chinese in having pseudoexfoliation (P > 0.05).

Table 1

Demographic characteristics and occurrences of pseudoexfoliation among patients who had undergone cataract surgery, Hospital Melaka, 2007-2014

Demographic variables	Patients with pseudoexfoliation (n=149), n (%)	Patients without pseudoexfoliation (n=12,843), n (%)	OR (95% CI)	P
Age (years), mean±SD	71.1±6.9	64.9±11.1	6.2 (8.0-11.0)*	<0.001***
Gender
Male	68 (45.6)	6042 (47.0)	1.00
Female	81 (54.3)	6800 (52.9)	1.05 (0.76-1.46)	0.732
Ethnicity
Chinese	35 (23.4)	4928 (38.3)	1.00
Malay	54 (36.2)	6155 (47.9)	1.24 (0.79-1.93)	0.331
Others	2 (1.3)	91 (0.7)	3.05 (0.74-12.49)	0.105
Indian	55 (36.9)	1553 (12.0)	4.99 (3.19-7.82)	<0.001***

*Mean difference, ***P<0.05, significant. OR: Odds ratio, CI: Confidence interval, SD: Standard deviation

Table 2 and Figure 1 depict the occurrences of different common intraoperative complications among patients who had undergone cataract surgery. These complications included zonular dehiscence, PCR, vitreous loss, and lens subluxation or dislocation. Among 12,992 patients, the most common intraoperative complication seen was PCR with 4.8%, followed by vitreous loss (3.1%), zonular dehiscence (1.1%), and lens subluxation or dislocation (0.3%). Vitreous loss was present either due to PCR or zonular dehiscence. Patients with overall complications were 2.68 times more likely to have pseudoexfoliation in comparison with those patients without complications (P < 0.001). We observed patients with pseudoexfoliation to have higher likelihood in presenting with lens subluxation, zonular dehiscence, and vitreous loss recording ORs of 6.92, 6.72, and 2.99, respectively (P < 0.001). However, there was no significant association among patients with pseudoexfoliation with PCR (P > 0.05).

Table 2

The occurrences of the intraoperative complications among patients with and without pseudoexfoliation who had undergone cataract surgery, Hospital Melaka, 2007-2014

Intraoperative complications	Patients with pseudoexfoliation (n=149), n (%)	Patients without pseudoexfoliation (n=12,843), n (%)	OR (95% CI)	χ2	P
Overall complications
Yes	32 (21.5)	1189 (9.2)	2.68 (1.77-4.04)	25.8	<0.001***
No	117 (78.5)	11,654 (90.7)
Zonular dehiscence
Yes	10 (6.7)	136 (1.1)	6.72 (3.26-13.48)	42.35	<0.001***
No	139 (93.3)	12,707 (98.9)
Posterior capsule rupture
Yes	6 (4.03)	617 (4.8)	0.83 (0.33-1.96)	0.19	0.658
No	143 (95.9)	12,226 (95.2)
Vitreous loss
Yes	13 (8.7)	398 (3.1)	2.99 (1.60-5.47)	15.22	<0.001***
No	136 (91.2)	12,445 (96.9)
Lens subluxation/dislocation
Yes	3 (2.0)	38 (0.3)	6.92 (1.69-23.70)	13.81	<0.001***
No	146 (97.9)	12,805 (99.7)

***P<0.05, significant. OR: Odds ratio, CI: Confidence interval

Figure 1

Intraoperative complications of cataract surgery

Table 3 shows the occurrences of different common postoperative complications in patients who had undergone cataract surgery. The total number of postoperative complications was noted to be small with 26 cases contributing to 0.2% of total 12,992 patients with the highest percentages provided by corneal decompensation at 0.18%, IOL decentration at 0.02%, and raised IOP at 0.01%. We did not observe any association between patients with pseudoexfoliation and any of the postoperative complications such as corneal decompensation (P > 0.05), raised IOP (P > 0.05), IOL decentration (P > 0.05), and overall complications (P > 0.05).

Table 3

The occurrence of the postoperative complications among patients with and without pseudoexfoliation, who had undergone cataract surgery, Hospital Melaka, 2007-2014

Postoperative complications	Patients with pseudoexfoliation (n=149), n (%)	Patients without pseudoexfoliation (n=12,843), n (%)	OR (95% CI)	χ2	P
Overall complications
Yes	0 (0.0)	26 (99.8)	0.00 (0.00-16.54)	0.30	0.582
No	149 (100.0)	12,804 (99.7)
Raised IOP
Yes	0	1 (0.01)	0.00 (0.00-1500.40)	0.01	0.914
No	149 (100)	12,842 (99.99)
Corneal decompensation
Yes	0	23 (0.18)	0.00 (0.00-18.80)	0.27	0.605
No	149 (100)	12,816 (99.82)
IOL decentration
Yes	0	2 (0.02)	0.00 (0.00-352.34)	0.02	0.878
No	149 (100)	12,837 (99.98)

P<0.05. IOP: Intra-ocular pressure, IOL: Intraocular lens, OR: Odds ratio, CI: Confidence interval

Table 4 shows the postoperative outcome of visual acuity in patients with and without pseudoexfoliation. The visual acuity outcome was grouped into three groups, i.e., good (6/6–6/12), impaired (6/18–6/36), and poor (6/60 and worse). We observed that of these 12,214 patients, 9491 (77.7%) patients had good vision, 1917 (15.7%) patients had impaired vision, and 806 (6.60%) patients had poor vision. We noted that patients with postoperative poor visual acuity outcome were 1.77 times more likely to occur in patients with pseudoexfoliation (P < 0.05). However, there was no association among patients with pseudoexfoliation with good and impaired visual acuity outcomes postoperatively (P > 0.05).

Table 4

Analysis of visual outcome in patients with and without pseudoexfoliation, in patients who had undergone cataract surgery, Hospital Melaka, 2007-2014

Visual acuity	Patients with pseudoexfoliation (n=149), n (%)	Patients without pseudoexfoliation (n=12,843), n (%)	OR	χ2	P
Good (6/6-6/12)
Yes	97 (71.32)	9394 (77.78)	0.71 (0.48-1.05)	3.23	0.072
No	39 (28.68)	2684 (22.22)
Impaired (6/18-6/36)
Yes	24 (17.64)	1893 (15.67)	1.15 (0.74-1.80)	0.396	0.529
No	112 (82.35)	10,185 (84.32)
Poor (6/60 and worse)
Yes	15 (11.03)	791 (6.55)	1.77 (1.00-3.11)	4.38	0.036***
No	121 (88.97)	11,287 (93.45)

***P<0.05, significant. OR: Odds ratio

Discussion

Only 149 (1.15%) of 12,992 patients had pseudoexfoliation, which occurred more in older individuals aged 71 years and above with a mean difference of 6.2 years compared to those without pseudoexfoliation. There was no difference in gender, but Indians had a higher likelihood of having pseudoexfoliation compared to Chinese, Malays, and other races. In a rural population presenting to Temerloh Hospital, Malaysia, the incidence of PXM was 1.59% (26 of 1632 patients) similar to the presentation in our state hospital.[6]

Pseudoexfoliation was found in 21.6% of the 1763 eyes undergoing cataract surgery in Spain between January 2013 and July 2013.[1] The frequency increased in age from 6.0% in those aged 50–60 years to 31.6% to those above 80 years. A study in Chennai also found the incidence increasing with age (P < 0.001).[7]

In Singapore, Indians were 5.04 times more likely to develop PXM than the Chinese (P < 0.001, 95% CI, 3.05–8.33), whereas the Malays were 2.22 times more likely to develop PXF as compared with the Chinese (P = 0.029, 95% CI, 1.08–4.55).[8]

Common intraoperative complications for all the 12,992 patients during cataract surgery in decreasing order were PCR, vitreous loss, zonular dehiscence, and subluxation/dislocation of the lens.

We found that the incidence of overall intraoperative complication was 2.68 times more likely among patients with PXM compared to those without PXM. Hemalatha and Shetty[9] found that cataract surgery in eyes with PXM had a higher rate of intraoperative and postoperative complications. However, Dwivedi et al.[10] and Hyams et al.[11] found no difference in intraoperative complications between those with PXM and those without.

Although PCR was the most common intraoperative complication (4.8%) for all cataract surgeries, there was no relationship between the presence of PXM and the occurrence of PCR. Thanigasalam et al.[12] also found no relationship between PXM and PCR in patients undergoing phacoemulsification. Spontaneous PCR in the presence of PXM is rare and a case has been described by Takkar et al.[13]

Patients with pseudoexfoliation had a higher chance of getting vitreous loss (seven times more), zonular dehiscence (seven times more), and lens subluxation/dislocation in our study. Thevi and Abas found that PXM was the only ocular comorbidity causing vitreous loss.[14]

Zare et al.[15] and Chen et al.[16] found that pseudoexfoliation was one of the factors associated with vitreous loss. The risk is increased through several mechanisms including zonular weakness and poor pupil dilatation. However, Nagashima[17] found no difference in those with PXM and in those without.

Using the random-effects model, the pooled OR was 2.1363 (95% CI, 1.5394–2.9648), which corresponds to a risk of >10% to get PCR or zonular dialysis in the presence of PXM during cataract surgery in a meta-analysis by Vazquez-Ferreiro et al.[18] We recommend using capsular tension rings (CTRs) for cases with PXM during phaco as no eye in the CTR group had intraoperative zonular separation (P = 0.02) in a study by Bayraktar et al.[19]

Lens dislocation was seen in six (3%) patients among those with PXM in a study by Jawad et al.[20] Ota et al.[21] studied the cases where dislocation of the lens occurred into the vitreous following hydrodissection in 1 of 10,126 cases. All four were elderly and one had PXM in the contralateral eye. They recommend careful hydrodissection in patients with PXM. Profuse and repeated cortical hydration may help soften cortex material and facilitate its aspiration. In all cases, slow-motion careful tangential stripping, in combination with gentle centripetal traction, should allow for accurate cortical removal.[22] We recommend examining the patient preoperatively and intraoperatively very carefully to look for phacodonesis, anterior chamber asymmetry, and excessive lens movement to minimize this complication.

The presence of PXM did not cause corneal decompensation although corneal decompensation was the highest postoperative complication among cataract patients. Loss of or damaged endothelial cells can lead to increased corneal thickness which can cause corneal decompensation. Ostern and Drolsum found that even 6–7 years following cataract surgery, corneal endothelial cell density and corneal cell thickness did not vary between eyes with PXM and those without.[23]

We found that patients with PXM had poor visual acuity compared to those without PXM. Poorer outcomes could be associated with the increase in intraoperative complications seen among patients with pseudoexfoliation. Thevi et al. found that good outcomes were seen in those cases who did not have complications.[2425] Dwivedi et al. also found that BCVA using Snellen chart with pinhole on postoperative day 1 was significantly better in the control group compared to the group with PXM (P = 0.027) in phacoemulsification.[10] However, Sufi et al.[26] also found no difference in visual outcomes in both the groups at 6 months (P > 0.05). Drolsum et al.[27] found that those with PXM had better outcome than those without PXM.

Conclusions

Patients with PXM had a higher rate of intraoperative complications which were mainly vitreous loss and zonular dehiscence and also lens subluxation/dislocation. We observed poorer visual outcomes in those with PXM following cataract surgery. Care should be taken to identify patients with pseudoexfoliation and precautions taken to minimize these complications to get better visual outcomes.

What was known

Pseudoexfoliation causes difficulty during phacoemulsification surgery due to zonular disintegration and difficulty in dilating the pupil.

What this paper adds

Although Malaysia is a developing country, we are also advancing as a nation by increasing the number of cataract operations. Our complication rates have reduced and we are achieving better outcomes compared to previous years and are leading toward our aim of better sight for all Vision 2020. This article of a study covering 8 years identifies the specific problems with cataract surgery among patients with pseudoexfoliation in our setting. Measures must be taken to identify and rectify/prevent those problems from occurring to achieving our goal by 2020.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.