Early intraocular pressure spike after phacoemulsification with intraocular lens implantation and goniosynechialysis in primary angle-closure glaucoma

Abstract

Purpose: To evaluate the characteristics and associated risk factors of early postoperative intraocular pressure (IOP) spike in patients undergoing phacoemulsification with intraocular lens implantation and goniosynechialysis in primary angle-closure glaucoma.

Design: Retrospective case series.

Patients and Methods: Patients with consecutive primary angle-closure glaucoma patients without previous incisional glaucoma surgery who had undergone phacoemulsification with intraocular lens implantation and goniosynechialysis (PEI-GSL) by the same surgeon between January 2017 and November 2019 were reviewed to obtain the demographic information, number of antiglaucoma medications, preoperative IOP, pre-operative peripheral anterior synechiae (P-PAS), axial length (AL), anterior chamber depth (ACD), lens thickness (LT), mean deviation (MD), as well as pattern standard deviation (PSD) of the visual field (VF), Optic Vertica Cup-to-Disc ratio (C/D), intraoperative PAS remain (I-PAS), and postoperative outcomes. A postoperative early IOP spike was defined as an IOP of at least 21 mmHg at 2 h post-operation. The main outcome parameters were the frequency and distribution of postoperative IOP spikes and the risk factors associated with an IOP spike after PEI-GSL.

Results: Of 100 eyes (100 patients) included in the study, 32% showed an early IOP spike (IOP spike group), while 68% showed no early IOP spike (no IOP spike group). Eleven patients (34.3%) from the IOP spike group showed an IOP value of ≥30 mmHg, and all underwent 2.82 times of aqueous humor release postoperatively. In the IOP spike group, twelve patients (37.5%) showed an IOP value of ≥21 mmHg at postoperative day (POD) 1, while three (9.4%) showed an IOP value of ≥21 mmHg at POD 7. The overall success rate was 89.74%, and the qualified success rate was 95.12% at the last follow-up (mean = 19.9 months, range 6–46 months). There was no significant difference in the frequency of IOP levels of ≥ 21 mmHg between the IOP spike group and the non-IOP spike group at the last visit (Fisher exact test, P = 1.000). Diagnosis of APACG or CPACG was associated with P-PAS, ACD, and PSD of VF but not with IOP spike (F = 4.003, P = 0.045).

Conclusions: A significant percentage of PACG patients undergoing PEI-GSL had IOP spike at 2 h postoperatively. Side-port release of aqueous humor and use of antiglaucoma medications can effectively reduce IOP within one week after surgery. IOP spike was observed more frequently in patients with CPACG than in patients with APACG at 2 h postoperatively. Postoperative IOP spike did not affect the long-term success rate of IOP control. 

1. Background

Primary angle-closure glaucoma (PACG) is a common subtype of glaucoma in China, which is characterized by progressive peripheral anterior synechiae (PAS) that lead to the permanent closure of the anterior chamber angle with an acute or chronic elevated intraocular pressure (IOP) and subsequent irreversible optic nerve damage ^[1]. PACG in Asia accounts for 70% of the global cases, and the rate of blindness is three times higher than POAG ^[2]. IOP is usually elevated when at least 180° of the drainage angle is closed, and topical IOP-lowering medications may not be sufficient to adequately lower IOP at this stage.

Goniosynechialysis (GSL) is a surgical procedure that strips the PAS from the angled wall to open the angle and restore trabecular function. It is a safe and effective therapy for angle-closure glaucoma ^{[3, 4]}. GSL combined with phacoemulsification was reported in 1999 as a successful alternative and potentially safer method than combined phacoemulsification and trabeculectomy in lowering the IOP in medically uncontrolled PACG ^[5]. GSL combined with cataract extraction, either by extracapsular cataract extraction or by phacoemulsification, is more effective than GSL alone in lowering IOP ^{[6, 7]}. Only two prospective, randomized, controlled trials have compared phacoemulsification with combined GSL to phacoemulsification alone, with contrasting findings. Lee et al. ^[8] reported no additional IOP-lowering benefit of GSL in medically well-controlled PACG patients with cataracts, while Shao et al. ^[9] reported that combined phacoemulsification and GSL resulted in significantly better IOP control. Shao et al. also demonstrated that GSL yields anatomical benefits, with a significantly greater improvement of the anterior chamber angle than phacoemulsification alone. A randomized controlled study ^[10] reported that the tonographic aqueous outflow facility (TOF) increased with phaco-GSL, from 0.099 ± 0.07 µL/min/mmHg to 0.194 ± 0.07 µL/min/mmHg (p = 0.0006), whereas the phaco group showed no significant change. Although IOP was reduced in both groups, phaco-GSL (46.0%) resulted in a more significant change compared to phaco alone (27.6%, p = 0.04). PEI-GSL is becoming crucial surgery in the treatment of primary angle-closure glaucoma in China ^[1].

However, as the newly-opened angle may not function well during early post-operation and the IOP spike may be more often seen in PEI-GSL, only a few studies have reported the characteristics of the IOP spike after PEI-GSL. This paper analyzes and reports the patients with PACG who had undergone PEI-GSL, summarizes the characteristics of the elevation and changes in IOP at 2 h, 1 day, 7days and at the last follow-up visit after surgery, and examines the association factors.

2. Patients And Methods

Patients and Study Design

This retrospective case series evaluated PACG patients that had undergone PEI-GSL between January 2017 and December 2019 at the center of glaucoma, Eye Hospital of Wenzhou Medical University, China. The study was approved by the Ethics Committee of the Wenzhou Medical University according to the guidelines of the Declaration of Helsinki.

The inclusion criteria were: (1) PACG was diagnosed according to the Guide to Chinese Glaucoma ^[1]. Primary glaucoma of angle-closure led to acute or chronic elevated intraocular pressure with or without changes to the glaucomatous optic disc and damage to the visual field. (2) The existence of visually significant cataracts. (3) In cases in which both eyes of one patient were eligible, the eye that underwent surgery first was chosen for the study. (4) The patients were followed up for at least 6 months. The exclusion criteria were: (1) Complicated, with dislocation of the lens. (2) Complicated, with active uveitis or other intraocular inflammation. (3) Previous trabeculectomy or other incisional glaucoma surgery. (4) Rupture of the posterior capsule, amputation of the suspensory ligament, and amputation of the root of the iris occurred during the surgery.

A comprehensive eye examination was performed in all cases. The IOP was measured using a non-contact tonometer (TX-200, Canon Inc). Three measurements were obtained, and the average values were calculated. AL and lens thickness were measured using ophthalmic biometry (IOL Master 2000, Carl Zeiss Inc.). ACD was measured using an ultrasound biomicroscope (UBM, Aviso, Quantel Medical Inc). VF was measured using visual-field automated perimetry (SITA-Standard 24–2 program, Humphrey, Carl Zeiss Inc). Gonioscopy, including dynamic (indentation) gonioscopy, was performed to confirm the diagnosis of angle-closure and assess the degree of synechia (assessed subjectively by the examiner). The numbers of antiglaucoma medications, corneal edema, hyphema, fibrinoid exudation, and length of operation were obtained from the medical records.

Patients were evaluated after surgery at 2 h, 1 day, 7 days, and the last follow-up visit. IOP spike was defined as an IOP level of ≥ 21 mmHg at 2 h postoperatively. Based on the occurrence of IOP spike, the patients were categorized into the IOP spike group and no IOP spike group. Complete success was defined as an IOP value of between 5 and 21 mmHg without antiglaucoma medications or further glaucoma surgery. Qualified success was defined as having an IOP value of between 5 and 21 mmHg and with or without antiglaucoma medications.

Surgical Technique

Proparacaine HCl (0.5%) was applied 10 minutes before surgery for topical anesthesia. Clear corneal phacoemulsification was performed through a 2.2 mm main incision and a 1 mm lateral incision. The subsequent procedures were performed in the order of continuous curvilinear capsulorhexis, phacoemulsification, removal of the residual cortex, and implantation of a foldable intraocular lens in the capsular bag. A viscoelastic agent (1 ml: 0.1 mg, Bausch & Lomb, Shandong, CN) was used to separate the posterior iris synechia in the anterior chamber. Using an intraoperative surgical gonioscope (Volk, G-2 Gonio or Ocular Instr. Ahmed DVX), the surgeon gently pressed against the peripheral iris with a blunt cyclodialysis spatula to exert a backward pressure on the iris until the trabecular meshwork was observed. After GSL, the residual viscoelastic was removed by automated irrigation/aspiration (I/A). The incision was closed using stromal hydration or a 10–0 nylon suture. The residual PAS of the angle was further evaluated at the end of the surgery. All surgical procedures were performed by the same surgeon (YBL). The antiglaucoma medications were discontinued after surgery. IOP was examined at 2 h after surgery. Lateral incision aqueous release was performed at an IOP level of ≥ 30 mmHg, and topical antiglaucoma medications were used at an IOP level of ≥ 21 mmHg at the POD1. All patients were prescribed tobramycin/dexamethasone eye drops (TobraDex, Alcon, Rijksweg, Belgium) four times daily over 2–4 weeks.

Statistical Analysis

Shapiro-Wilk test was used to evaluate the categorical parameters. Normally distributed continuous data were expressed as mean (SD), Non-normally distributed continuous data were expressed as the median (minimum-maximum), and categorical data were presented as percentages. An Independent 2-tailed t-test was used to compare the groups for normally distributed continuous variables. Mann-Whitney U test was used to compare the groups for non-normally distributed continuous variables. The Chi-square test was used to compare the groups for categorical variables. Factors related to IOP spike were analyzed using logistic regression analysis. The variables for multivariable analysis were selected from those with a probability p-value of < 0.20, as determined by univariable analysis. A p-value of < 0.05 indicated statistically significant differences. For a two-sided test, the level of significance was 0.05. The statistical analysis was performed using the statistical program SPSS for Windows, version 26.0 (IBM-SPSS Inc).

3. Results

Patient demographics

This study was conducted on 100 eyes (100 patients). The mean follow-up period was 19.7 ±9.8 months (range 6-46 months). Table 1 provides the characteristics of all 100 eyes (100 patients) at baseline.

   Of 100 eyes (100 patients) included in the study, 32 eyes (32%) had an early IOP spike, and the mean IOP was 28.1 ±13.1 (21.1 – 53.5) mmHg. Eleven eyes (11/32, 34.3%) in the IOP spike group had an IOP of ≥ 30 mmHg and underwent an average of 2.82 ±1.48 (1, 9) times lateral incision aqueous release. The Mean IOP in the IOP spike group at POD1 was 18.48 ±8.45 (21.1 – 36.7) mmHg, and the mean number of antiglaucoma medications was 0.84 ±1.39. 

The mean IOP in the IOP spike group at POD7 decreased to 14.38 ±6.12 (21.8 – 33.1) mmHg, and the mean number of antiglaucoma medications was 0.35 ±0.67. The overall success rate was 89.7%, and the qualified success rate was 95.1%. The mean IOP at the last follow-up was 14.2 ±3.7 mmHg, and the mean number of antiglaucoma medications was 0.61 ±1.10 (mean 19.68 m, 6–46 m) (Fig. 1). 

The rate of IOP spike at 2 h postoperatively, POD1, POD7, and last follow-up was 32%, 19%, 6%, and 4%, respectively (Fig 2). Four eyes (four patients), which had a high IOP at POD7, showed a decrease in the IOP to normal after an average of 8.25 (4–12) days. There was no significant difference in the frequency of IOP level of ≥ 21 mmHg between the IOP spike group (%) and the no-IOP spike group (%) at the last visit (Fisher exact test, P = 1.000).

IOP spike was observed more often in patients with chronic primary angle-closure glaucoma (%) compared to those with acute primary angle-closure glaucoma (%), (F = 4.003, P = 0.045). Patients with an IOP spike showed a more severe MD value of VF compared with those in the no-IOP spike group (U = 525.000, P = 0.014). No other preoperative, intraoperative, and postoperative variables were observed to be associated with the IOP spike (all P-values > 0.05) (Table 2). In a logistic regression model, P-PAS, ACD, and PSD of VF were not correlated with the IOP spike (Table 3). 

4. Discussion

PEI-GSL is becoming an increasingly popular treatment for PACG ^[11]. It has a good long-term effect of lowering IOP, even in PACG patients with failed trabeculectomy ^{[12, 13]}. In this study, the range of PAS in the included patients was 241.12 ± 100.57°, and the mean IOP was 28.6 ± 15.4 mmHg combined with three antiglaucoma medications. The overall success rate was 89.7%, and the qualified success rate was 95.12% at the last follow-up (mean 19.9 months,6–46 months).

There is no widely accepted standard for the definition of the IOP spike. A common definition of an IOP spike is the increase in IOP over 30 mmHg in the early postoperative period. Less frequent definitions include the incidence of IOP of over 28 mmHg ^[14] or 40 mmHg ^[15]. Some authors prefer to use a relative value, for example, a 50% increase in IOP ^[16] or an increase by 10 mmHg ^[17]. The IOP spike typically peaks at 3–7 h after phacoemulsification (PEI) and persists during the first 24 h. The most hazardous time for glaucoma patients is at 3–4 h postoperatively, when most of the eyes have an elevated IOP level of over 30 mmHg ^{[14, 18]}. To detect early postoperative elevated IOP, we routinely examined IOP at 2 h after surgery and defined the early IOP spike as IOP ≥ 21 mmHg at 2 h after PEI-GSL.

In our study, 32 eyes (32%, 32/100) showed an early IOP spike, including 11 eyes (11/32, 34.3%) that had IOP levels of ≥ 30 mmHg. Ahmed et al. ^[14] reported a significant increase in the mean IOP levels from baseline to 3 to 7 h postoperatively in both glaucomatous (10.2 mmHg) and non-glaucomatous (4.1 mmHg) eyes, with a significant number of patients having an IOP of at least 28 mmHg in the glaucomatous group (46.4%) and non-glaucomatous group (18.4%), Particularly worrisome is the finding that 18.8% of the patients with glaucoma and 3.6% without glaucoma had an IOP of above 40 mmHg. The incidence of IOP spikes was higher than our result, which may be related to the selection of cases and the mode of operation. Those cases did not reveal the type of glaucoma, and the surgical method was PEI. Our study only included PACG and PEI-GSL as the interventional procedure.

Our findings emphasize the need for vigilance in monitoring and treating postoperative IOP, especially in patients with PACG. In patients with an IOP of ≥ 30 mmHg at 2 h after surgery, anterior chamber fluid was released through the lateral incision an average of 2.82 times, which rapidly reduced the IOP and protected the further damage of optic nerves in glaucoma. IOP levels of > 21 mmHg were observed in 19% of the patients at POD1 and 4% at POD7. A meta-analysis ^[19] demonstrated that glaucoma was a significant risk factor for retinal vein occlusions, and there was a plausible relationship between PACG and risk of RVO (OR: 1.85; 95% CI: 0.41–8.35). Moreover, the early postoperative elevation of intraocular pressure in patients with glaucoma may lead to optic neuropathy and visual field progression. The mean deviation of VF was significantly aggravated only in the PACG group (from − 7.26 to − 8.82 dB, P < 0.001) ^[20]. Nowadays, day surgery for glaucoma care is trending, although the high rate of IOP spike and the potential harm may deter the application of day surgery for glaucoma patients.

The overall mechanism of the IOP spike was not clear. It was believed that PEI postoperative IOP spike of PACG was also previously seen in penetrating canaloplasty. About 40% of the patients in PACG showed an IOP spike (≥ 21 mmHg) after penetrating Schlemm canaloplasty, and the IOP dropped below 21 mmHg within 7 days to 3 months after surgery.^[21] In this study, IOP decreased within 7 days after PEI-GSL. This rapid decrease of IOP may be attributed to the normal function of distal outflow pathways, such as the trabecular network, Schlemm’s canal, collector tube, and aqueous humor vein in PACG. The removal of the lens can eliminate the pupil block, substantially deepen the anterior chamber, widen the chamber angle, or separate the PAS with GSL as much as possible to resume the drainage function of the anterior chamber angle. The incidence of PACG patients with IOP spike that underwent penetrating Schlemm canaloplasty was higher, and the duration was longer than those with PEI-GSL. This difference may be attributed to the fact that penetrating Schlemm with an iTrack-illuminated microcatheter may somewhat destroy the microstructure of the Schlemm canal and affect the restoration of aqueous humor drainage function. PEI-GSL only exposes the trabecular network and removes the mechanical obstruction of the trabecular network, which may not destroy the microstructure of the Schlemm’s canal. Ahmed et al. ^[14] reported IOP of > 28 mmHg in 18% of the non-glaucoma patients in the early (3–7 h) postoperative PEI period, which decreased to baseline level within 4 days in most individuals. Our results agree with the study by Ahmed et al. ^[14], although our study defined the standard IOP spike as ≥ 21 mmHg, which was lower than their results. In our study, the IOP spike at 2 h post-operation was not associated with the intraoperative residual PAS, length of operation, postoperative cornea edema, fibrinous exudate, and postoperative hyphemia.

Previous studies have demonstrated that the postoperative IOP can be well-controlled by phacoemulsification and IOL implantation alone for patients with angle-closure glaucoma, accompanied by PAS of < 180°, whereas patients with excessive chamber angle adhesion GSL should be considered to separate these adhesions ^[22]. However, we believe that we should also routinely combine phacoemulsification with GSL for patients with PAS of < 180° to separate the PAS as much as possible, protect the drainage function of the angle, and avoid the progression of synechia, which may ultimately increase the IOP.

The risk factors for IOP spikes following PEI include residual viscoelastic material ^{[23, 24]}, resident-performed surgery ^{[17, 25, 26]}, glaucoma ^{[14, 16]}, exfoliation syndrome ^[27], an axial length of more than 25 mm ^[28], and topical steroid application in steroid responders ^[29]. However, a few studies have reported the associations of IOP spike after PEI-GSL in PACG. In our study, patients with IOP spike had severe visual field defects compared to those without IOP spike. Also, IOP spike was more often observed in CPACG (44%) than in APACG (25%). This may indicate that the PAS was formed for a longer time in CPACG and the peripheral iris tissue adhered more closely to the trabecular meshwork. It was observed that the separation of PAS in CPACG was more difficult than that in APACG, and there was more pigmentation of the iris attached to the trabecular meshwork of CPACG. However, the situation of chamber angle pigment and angle-separation time of the two groups were not recorded, and the degree-wise classification of trabecular meshwork pigment and separation time of GSL in different types of PACG was not analyzed. In the multifactorial regression model, pre-PAS, ACD, and PSD of VF were not correlated with IOP spike.

The mean follow-up period was 19.7 ± 38.5 months (range 6 to 46 months). The overall success rate was 89.74%, and the qualified success rate was 95.12%. The mean IOP was 14.48 ± 3.66 mmHg, and the number of mean antiglaucoma medications was 0.61 ± 1.10 at the last follow-up. Four eyes (4/100, 4.00%) needed to undergo anti-glaucoma surgery again. This finding was consistent with the study by Kameda et al.^[30], who reported that the probability of treatment success for all 109 eyes was 85.9%, with a mean follow-up of 40 months after Phaco-GSL, while the study by Teekhasaenee et al.^[5] reported that out of the 52 eyes that underwent Phaco-GSL, 47 eyes (90.4%) and four eyes (7.69%)had an IOP of > 20 mmHg without and with the use of medications, respectively, with a follow-up of 20.8 months. A previous study ^[31] has demonstrated that the trabecular meshwork may be irreversibly damaged, and even the PAS is reopened to expose the trabecular network. These functions cannot be restored in PACG patients who have experienced long-term angle closure. Compared to the rate of success of conventional trabeculectomy, we believe that GSL is worth trying for patients with long-term angle closure and exposure to the functional trabecular network is vital.

There was no significant difference in the incidence of IOP of ≥ 21 mmHg between the IOP spike group and the non-IOP spike group at final follow-up. This result indicates that the early IOP spike was not related to the long-term success rate of IOP control.

In our study, the average residual PAS was 37.73 ± 54.99° at the end of the operation. However, there are no sufficient animal or human studies to determine the extent of recovery of the trabecular meshwork function after reopening the PAS, and the separation of PAS during operation depends entirely on the subjective judgment of the surgeon.

5. Limitations

This study was a retrospective study covering only Chinese people. The long-term effectiveness of PEI-GSL and the effect of iris pigment attachment on the trabecular meshwork function and IOP spike need to be investigated further. Moreover, the same surgeon performed all cases, and the extrapolation of these results to different surgical techniques may be incorrect.

6. Conclusion

In summary, PEI-GSL is an effective treatment method for PACG patients. A significant percentage of PACG patients showed an IOP spike after PEI-GSL. Close postoperative care and interventions at an early stage are needed to prevent potential harm induced by IOP spike.

Declarations

Ethics approval and consent to participate： The study complied with the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of the eye hospital of Wenzhou Medical University(YX2018-016). All included patients gave their oral and written informed consent.

Consent for publication: Not applicable.

Competing interests: The authors declare that they have no competing interests.

Funding:  This work was supported by National Key R&D Program of China (2020YFC2008200), Key Research and Development Program of Zhejiang（2022C03112）.

Authors' contributions：L Yu and  Y Y Li conceived of the presented idea. L Yu , Y Y Li , J J Zuo and Y B Liang developed the theory and performed the computations;  L Yu , Y Y Li , J J Zuo , Y H Tang: Data Curation, Writing - Original Draft; G X Li: Visualization, Investigation;  S D Zhang: Resources, Supervision; Q Zhang: Software, Validation;   Y B Liang (Corresponding Author): Conceptualization, Funding Acquisition, Resources, Supervision, Writing - Review & Editing.All authors discussed the results and contributed to the final manuscript.

Acknowledgement：In this study, there is no conflict of interest, commercial affiliations, consultations, stock or equity interests, source of financial grants and other funding.

Authors ' information : Lei Yu, MD, Master degree; Yao-yao Li, Present Gradudate students, Master degree; Jing-jing zuo , MD, Master degree; Yi-hua Tang, MD, Master degree; Guo-xing Li, MD, PhD; Shao-dan Zhang, MD, PhD;  Qi Zhang, MD,PhD; Yuanbo Liang, MD, PhD.

Availability of data and materials: The datasets generated and/or analysed during the current study are not publicly available due the  datasets come from hospitalized cases, and electronic cases are counted retrospectively, but are available from the corresponding author on reasonable request. 

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