Cataract surgery in pseudoexfoliation syndrome

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INTRODUCTION

Cataracts are one of the primary causes of reversible blindness in the world [1]. Usually, cataracts develop because of the aging process; however, the presence of pseudoexfoliation syndrome (PEX) also induces sclerotic changes in the lens nucleus [2, 3]. Phacoemulsification (PE) is the primary method of surgical treatment for cataracts.

PEX, an age-related disease that affects many organs and systems, is based on the production and accumulation of fibrillar material in various tissues of the body. Most often, pseudoexfoliation material (PEM) appears on the anterior capsule of the lens, the pigment epithelium of the iris, the ciliary body, ciliary zonules, and the corneal endothelium [4–6]. It is reasonable to assume that PEM accumulations are caused by morphological changes in the anterior eye, which, in turn, can theoretically complicate the PE course, causing a variety of intra- and postoperative complications [5]. The most common intraoperative complications are ruptures of ciliary zonules and posterior capsule, and vitreous body prolapse. The most common postoperative complications include intraocular inflammation, opacification of the posterior lens capsule, phimosis of the anterior lens capsule, and various degrees of intraocular lens (IOL) dislocation [7].

This study aimed to investigate the effect of PEX on the course of PE.

PATIENTS AND METHODS

This study was conducted at the Ophthalmology Department No. 5 of the City Multi-Field Hospital No. 2. We examined 1010 patients admitted for cataract surgery. The presence of PEX was considered fundamental in the distribution of the patients into two groups: those with PEX (main group, n = 580 patients) and those without PEX (control group, n = 430 patients). PEM was detected by biomicroscopy with undilated and dilated pupil or gonioscopy. The patients in the main group had pseudoexfoliation material in the anterior chamber angle, on the anterior lens capsule, or the pupil margin of the iris. PEX was also diagnosed in the presence of its early stage in the form of a homogeneous PEM layer on the anterior capsule of the lens. Patients were diagnosed with latent PEX if the PEM layer on the anterior lens capsule could not be visualized due to insufficient medicamentous mydriasis (≤4.5 mm), but they had signs such as pigment dispersion on the corneal endothelium, defects in the pigment leaf of the iris at transillumination, and sub-atrophy of the iris stroma. The detection of these signs in the fellow eye only was insufficient to establish a clinical diagnosis of PEX. The groups were equal in terms of sex and age (Table 1).

 

Table 1 / Таблица 1 Распределение групп пациентов по полу и возрасту Distribution of groups by gender and age
Indices		PEX group (main, n = 580)	Group without PEX (control, n = 430)	Significance of difference
Age		73.8 ± 3.8	72.9 ± 4.1	P = 0.51
Sex	Male	116 (20%)	143 (33.3%)	P = 0.21
	Female	464 (80%)	287 (66.6%)

 

All patients underwent a standard preoperative ophthalmological examination. PE was performed as a method of cataract surgery by the same surgeon using the phacochop technique (Infiniti, Alcon), with implantation of various IOL types. Possible intraoperative complications were assessed, namely Descemet’s membrane detachment, the retrolental position of the lens material, posterior capsule rupture, and zonular dialysis. The classification of complications according to their severity is presented below.

We assessed the Descemet’s membrane detachment and the lens material retrolental position using a point system. If Descemet membrane was detached, the detachment’s severity was evaluated. If it was local, the severity corresponded to 1 point; if it was extensive, requiring introducing air into the anterior chamber, the severity corresponded to 2 points.

The surgeon assessed the retrolental lens material at the end of the procedure by a detailed examination of the anterior vitreous using the surgical microscope. The presence of a small number of dusty inclusions corresponded to 1 point, a moderate amount of dusty inclusions corresponded to 2 points, and single small fragments corresponded to 3 points.

We divided cases of zonular dialysis and posterior capsule rupture into those with vitreous prolapse and those without.

Cataract density was assessed by biomicroscopy at pupil dilated according to the Lens Opacities Classification System, version III [8].

We evaluated the main PE parameters, namely cumulative scattered ultrasound (US) energy, the amount of aspirated balanced salt solution (BSS) in ml, and the time of the surgery (from the moment the surgeon pressed the pedal of the phacomachine) in minutes. Statistical data were processed using SPSS Statistics v 20.0 (IBM Corp., Armonk, NY). Mean values and mean-square deviations were the primary indices of the statistical processing of quantitative indices. The t-test was used to assess the ratio of quantitative variables in 2 independent groups, whereas the construction of contingency tables was used to determine the ratio of qualitative variables.

RESULTS

The lens nucleus density was estimated using the Lens Opacities Classification System III at biomicroscopy [8]. We compared the frequency of occurrence of different nucleus densities in groups as well as the average score. Table 2 presents the distribution of nucleus density. For PEX patients, the presence of a dense lens nucleus was more characteristic. The average score in the PEX group was 3.5, whereas the average score in the group without PEX was 3.2 (P < 0.0001). In patients with PEX, the density of the nucleus NC4 was most common, whereas the density of the nucleus in patients without PEX was NC3 (P < 0.05) (Table 2).

 

Table 2 / Таблица 2 Assessment of cataract density in groups (LOCS III) Оценка плотности катаракты в группах пациентов (LOCS III)
Cataract density	PEX group (n = 580)	Group without PEX (n = 430)	Significance (P value)
NC2	54 (9.3%)	60 (14%)	0.174
NC3	203 (35%)	230 (53.5%)	0.011
NC4	301 (51.9%)	132 (30.7%)	0.0001
NC5	16 (2.8%)	7 (1.6%)	0.112
NC6	6 (1%)	1 (0.2%)	0.127
Note. LOCS, Lens Opacities Classification System; PEX, pseudoexfoliation syndrome.

 

For PE of denser nuclei in patients with PEX, it was necessary to spend more US energy. The cumulative dissipated energy of US was significantly higher in PEX patients (P = 0.045). The amount of aspirated BSS and the time of surgery were slightly higher in the PEX group. Still, the difference did not reach the level of statistical significance (P = 0.32 and 0.22, respectively) (Table 3).

 

Table 3 / Таблица 3 Phaco parameters in groups Параметры факоэмульсификации в группах пациентов
Indicator	PEX group	Group without PEX	Significance (P value)
Cumulative scattered ultrasound energy	17.3	14.1	0.045
Amount of aspirated BSS, ml	67.6	64.8	0.32
Time of surgery, min	7.73	7.28	0.22
Note. BSS, balanced salt solution; PEX, pseudoexfoliation syndrome.

 

Within the study, Descemet’s membrane detachment was local in all cases and observed in patients of both groups. However, this complication was more characteristic to the main group and occurred almost twice as often (P = 0.017) (Table 4). A retrolental location of the lens material at the end of uncomplicated PE, which is a marker of relaxation of lens ligaments, was found in 16.9% of patients with PEX and only 6% of patients without PEX (P = 0.001). There were no ruptures of the posterior capsule in either group (Table 4). Zonular dialysis was registered in four PEX patients, two of whom also experienced vitreous prolapse (P = 0.22) (Table 4). Moreover, there was no statistically significant difference between the groups. In this case, the contingency table was used for evaluation. As in the PEX group, four patients (<1%) had zonular dialysis, and 574 did not. It is worth noting that in each of these patients, IOL was implanted in the capsular bag after preliminary implantation of the intracapsular ring. In all other cases, the intracapsular ring was not implanted.

 

Table 4 / Таблица 4 Intraoperative complications in groups Структура интраоперационных осложнений в группах
Indicator	PEX group (n = 580)				Group without PEX (n = 430)			Significance (P value)
Descemet’s membrane detachment (local)	86 (14.8%)				34 (7.9%)			0.017
Retrolental lens material	98 (16.9%)				26 (6.0%)			0.0001
	1	2		3	1	2	3
	65 (11.2%)	33 (5.7%)		–	20 (4.7%)	6 (1.4%)	–
Posterior capsule rupture	0				0			–
Zonular dialysis	4 (0.7%)				–			0.26
	2 (0.35%) (with vitreous body prolapse)		2 (0.35%) (without vitreous body prolapse)
Note. PEX, pseudoexfoliation syndrome.

 

DISCUSSION

PEX undoubtedly complicates the task of the surgeon. This is most often due to the presence of a narrow pupil, relaxation of ligaments, and often a combination of both [5, 9–11]. Successful PE in this category of patients is based on a thorough preliminary examination, increased alertness, and compliance with several rules during surgery, as well as longer follow-up in the postoperative period.

The results of this study demonstrated that a dense lens nucleus is characteristic of PEX. In this regard, the surgeon must use more US energy. With PEX, the risk of the Descemet’s membrane detachment increases, which was local in all patients in this study and did not require air to be introduced into the anterior chamber or other measures. Another significant factor is the relaxation of ligaments of the lens, which is indicated by the appearance of small fragments of the lens material in the anterior vitreous, even during uncomplicated surgery.

There were no ruptures of the posterior capsule during the study. However, in the PEX group, there were four cases of zonular dialysis, two of which were accompanied by vitreous prolapse. This fact emphasizes once again the need to use in PEX surgical techniques that have a minimal impact on the ciliary zonules. In all cases of zonular dialysis, it was possible to straighten the capsular bag using the intracapsular ring and perform standard IOL implantation.

The preoperative assessment of the relaxation of ligaments is particularly noteworthy. Shallow anterior chamber, iridophacodonesis, zonular dialysis, and the gap between the iris and lens indicated the presence of the latter at biomicroscopy [9, 12–15]. PEM accumulations, both in the ciliary zonules and on the ciliary processes, cause the ligamentous apparatus instability [9, 16]. The literature indicated that in 8.4% to 10.6% of PEX patients, there is a subluxation of the lens of various degrees or phacodonesis [9, 13, 17, 18]. Vitreous herniation in the absence of PEX is noted five times less frequently than in the presence of PEX (9.0% and 1.8%, respectively) [19]. The latter, in turn, is associated with an increased occurrence of zonular dialysis, lens subluxation, and rupture of the lens capsule [19].

What rules must be followed during PE in the presence of PEX in a patient? First, attention should be paid to the size of capsulorrhexis owing to the fact that its small size will contribute to additional stress on the ligamentous apparatus of the lens. Moreover, the high risk of developing capsulophimosis in the postoperative period should not be neglected, as it could cause additional stress on the ligamentous apparatus. The optimal size of capsulorrhexis is believed to be 5.5 mm. Overfilling of the anterior chamber should be avoided during hydrodissection and hydrodelineation. Rotation should be performed as carefully as possible, preferably bimanually. With severe relaxation of the ligaments, a capsular ring must be used. The choice of PE technique depends largely on the surgeon. In this study, we used the phacochoр technique, which enables the surgeon to exert minimal pressure on the ligamentous apparatus and perform all manipulations in the center of the anterior chamber. Particular attention should be given to the washout of the lens masses, which can be quite challenging when the ligamentous apparatus of the lens is relaxed and in the presence of an intracapsular ring. The general rule when performing this stage is the tangential orientation of the movements [9, 14–20].

CONCLUSIONS

Based on our results, PE can be performed successfully in PEX patients. A large number of contemporary techniques and additional devices reduce the risk of various complications. However, this group of patients requires a more thorough preoperative examination, extra caution during surgery, and more careful and long-term postoperative follow-up. To achieve an optimal result, the surgeon must take into account all specific eye changes occurring in PEX.

About the authors

Vitaly V. Potyomkin

Academican I.P. Pavlov First St. Petersburg State Medical University; City Ophthalmologic Center of City Hospital No. 2

Email: potem@inbox.ru

PhD, Assistant Professor, Department of Ophthalmology; Ophthalmologist

Russian Federation, Saint Petersburg

Elena V. Goltsman

City Ophthalmologic Center of City Hospital No. 2

Author for correspondence.
Email: ageeva_elena@inbox.ru

ophthalmologist

Russian Federation, Saint Petersburg

References

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