Graefes Arch Clin Exp Ophthalmol DOI 10.1007/s00417-015-2931-4

GLAUCOMA

Canaloplasty versus non-penetrating deep sclerectomy – a prospective, randomised study of the safety and efficacy of combined cataract and glaucoma surgery; 12-month follow-up Marek Rękas & Anna Byszewska & Katarzyna Petz & Joanna Wierzbowska & Anselm Jünemann

Received: 18 November 2014 / Revised: 5 January 2015 / Accepted: 7 January 2015 # Springer-Verlag Berlin Heidelberg 2015

Abstract Purpose To compare outcomes of phaco-canaloplasty (PC) and phaco-non-penetrating deep sclerectomy (PDS) with a viscoelastic compound. Methods This study included 29 eyes after PC and 30 after PDS. Indications were uncontrolled primary open-angle glaucoma (POAG) and a cataract. Corrected distance visual acuity (CDVA), intraocular pressure (IOP), and number of medications were evaluated. Follow-up examinations were performed on days 1 and 7, and after 1, 3, 6, and 12 months. Complete and qualified success was an IOP ≤ 18 mmHg. Results At the 12-month follow-up, mean IOP decreased in the PC group from 19.0±6.9 mmHg to 12.6±2.7 mmHg, and in the PDS group, from 19.1±5.8 mmHg to 14.3±3.5 mmHg (P< 0.05). Both groups preoperatively and at 12 months showed no significant differences in IOP (P>0.05). There was no statistically significant difference between the number of medications used (P>0.05). Complete and qualified success rates for both groups were 79.0 % and 76.9 % (P=0.701). The most frequent postoperative PC complication was hyphema (58.0 %); for PDS, bleb fibrosis was most frequent (26.7 %). No PC patients required postoperative management. PDS patients required postoperative interventions 58.7 % of the time, including a 5-fluorouracil (5-FU) injection (58.7 %), suture lysis (48.3 %), and needling (27.6 %). M. Rękas : A. Byszewska : K. Petz : J. Wierzbowska Department of Ophthalmology, Military Institute of Medicine, Szaserów 128 STR., 04-141 Warsaw, Poland A. Jünemann Department of Ophthalmology, University Hospital Rostock, Doberaner Straße 140, 18057 Rostock, Germany M. Rękas (*) 63 Karol Szymanowski St., 05-270 Marki, Poland e-mail: [email protected]

Conclusions Both PC and PDS lead to an effective decrease in IOP on a short-term follow-up basis and demonstrate similar efficacy and safety profiles. PDS patients required additional procedures including 5-FU injections, suture lysis, or needling. PC patients required no additional procedures. Keywords Phaco-canaloplasty . Phaco-deep sclerectomy . Uncontrolled primary open angle glaucoma . Cataract Introduction Non-penetrating deep sclerectomy (DS) was introduced by Fyodorov and Kozlov in 1989 [1]. Six years later, Stegmann described and published the concepts of viscocanalostomy, and its further modification led to the development of canaloplasty [2]. Canaloplasty is a relatively new procedure, introduced in 2007 by Lewis [3]. Nonetheless, it has been gaining substantial interest among surgeons over the last few years [4–9]. The surgical techniques of canaloplasty and DS have a lot in common [10]. A precise dissection of the trabeculoDescemet’s membrane is of vital importance in both procedures. The external wall of Schlemm’s canal is additionally de-roofed in DS. During canaloplasty, the entire circumference of Schlemm’s canal is dilated and extended with a viscoelastic compound, followed by placement of 10/0 polypropylene sutures in the canal under tension. In the final part of both procedures, the superficial flap is closed with 10–0 monofilament nylon sutures. In phaco-DS (PDS), sutures are applied loosely to enable subconjunctival outflow. In phacocanaloplasty (PC), sutures should close the intrascleral lake so that it is watertight. In functional terms, the aqueous humour exits the anterior chamber via internal outflow in canaloplasty, and in DS, this exit mechanism depends greatly on subconjunctival outflow. It should be emphasised that other

Graefes Arch Clin Exp Ophthalmol

outflow pathways also function in DS, such as unconventional outflow and through newly developed intrascleral veins that form postoperatively around the scleral lake [11]. T h ere are o nl y fi v e co mp arat i v e s t u dies on canaloplasty in the literature to date. Three of them compare it with trabeculectomy and these are retrospective analyses of PC and phaco-trabeculectomy as well as canaloplasty and trabeculectomy [12–14]. There are also two prospective and comparative papers comparing viscocanalostomy and canaloplasty, but they are nonrandomized [6, 15]. To date, there are no comparative, prospective, and randomized studies concerning canaloplasty. As canaloplasty is gaining great interest among surgeons and patients, it should find its own place in a plan of surgical glaucoma treatment. The aim of this paper is to assess the short-term safety and efficacy of combined PC compared with PDS.

Materials and methods Patients The tenets of the World Medical Association Declaration of Helsinki and the principles developed by the European Union entitled Good Clinical Practice for Trials on Medical Products in the European Community were followed in this study. The project was approved by the Bioethics Committee of the Military Institute of Medicine in Warsaw. The study was registered at www.clinicaltrials.gov NCT01726543. Indications for surgery were coexisting glaucoma and a cataract (NC1 and NC2) classified according to the LOCS III scale. Included glaucoma types were primary open-angle glaucoma (POAG), pseudo-exfoliation glaucoma (PEX), and pigmentary glaucoma (PG), with unsatisfactory intraocular pressure (IOP) control despite maximally tolerated topical and systemic medication. Additional inclusion criteria included the following: well documented progression of the visual field [16, 17]; daily fluctuations in pressure; non-compliance in anti-glaucoma therapy; or allergy to topical medications. Written consent was obtained from all of the participants after they were informed about the character of the procedure and the surgical alternatives, and after declaring their willingness to participate in the study for at least 12 months. Exclusion criteria were unwillingness to participate, any previous surgical procedure within the eye, closed or narrow angle glaucoma, neovascular glaucoma, poorly controlled diabetes mellitus with diabetic retinopathy, advanced macular degeneration, and active inflammatory disease. There were 59 patients recruited into the study, and 29 eyes underwent phaco-canaloplasty (PC) while 30 eyes underwent PDS. Enrollment into groups was carried out by a random

sorting algorithm with an allocation ratio set to 1.0 on the day of surgery. Preoperative examination Patient medical history of previous ophthalmic treatment and surgical procedures was taken at the time of qualification. Before surgical intervention, all patients underwent a baseline examination that included determination of IOP, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and examination of the anterior and posterior segment. Cataract grading was assessed using the LOCS III scale. In addition, measurements were taken of the central corneal thickness (CCT), the axial length (AXL), the keratometric parameters required for the intraocular lens (IOL) calculation, and gonioscopy. IOP was measured during the preoperative visit as a diurnal curve and on the day of surgery, as a single measurement, in line with AGIS. A single measurment was taken with a Goldmann applanation tonometer on a slit-lamp biomicroscope. The reading in mmHg was rounded to the next higher integer. Each measurement was repeated, and if the two readings differed by three mmHg or more, a third measurement was taken. The median of the two or three measurements became the IOP determination and was taken into account in the analysis. IOP was measured during the preoperative visit as a diurnal curve and on the day of surgery as a single measurement between 8 and 10 am. The IOL was calculated on the basis of the Sanders, Retzlaff, and Kraft SRK T formula. The anterior and posterior segment were evaluated for fulfillment of the examination criteria. Surgical technique All surgical procedures were performed under retrobulbar anaesthesia (2 % xylocaine and 0.5 % bupivacaine) by one surgeon (M.R.). In both procedures, a fornix-based conjunctival flap was dissected superiorly, and the sclera was exposed. A 5.0 x 5.0 mm scleral superficial flap (parabolic in shape in PC and square-shaped in PDS) was dissected anteriorly into the clear cornea using a method previously described by Bellucci and Morseli [18]. Afterwards, the deep scleral flap and trabeculo Descemet’s membrane (TDM) were dissected. Then, a 2.2-mm clear corneal temporal phacoemulsification was performed using the Infiniti Vision System (Alcon Surgical, Fort Worth, TX), and an IOL was implanted. As soon as the phacoemulsification was done the cumulative dissipated energy (CDE) was noted, whereas after implanting the IOL and rinsing the anterior chamber, the aspiration time (AT) was determined. When performing PC, a microcatheter (iTrack 250A, iScience Interventional, Menlo, Park, CA) was placed in Schlemm’s canal and was advanced for 12 hours within the canal. Once the catheterisation of the canal was done, the

Graefes Arch Clin Exp Ophthalmol

distal tip was exposed and a 10–0 polypropylene suture was tied to the distal tip. Then, the microcatheter was withdrawn and the suture was pulled into the canal. The surgeon observed the location of the beacon tip through the sclera and injected viscoelastic compound every two hours. As the microcatheter appeared at the other ostium of the canal, the it was separated from the suture. A loop was created, encircling the inner wall of Schlemm’s canal. Then, the suture loop was tightened to distend the trabecular meshwork inward. The sutures were placed under tension and locking knots were added. During PDS, the dissection was made downwards to r e m o v e t h e r o o f o f S c h l e m m ’s c a n a l a n d t h e juxtacanalicular trabeculum after excision of the deep flap. Excision of the corneal stroma in both procedures was performed more anteriorly down to Descemet’s membrane. In the case of PDS, the superficial scleral flap was then closed with two 10–0 monofilament nylon sutures, and slowly resorbable crosslinked viscoelastic gel (HealaFlow, Anteis Ophthalmology, Geneva, Switzerland) was injected under the flap to create a filtering bleb [19]. In PC, however, the superficial flap was sutured tightly in order to prevent leakage and subsequent bleb formation. The conjunctiva was sutured down over the limbus with one interrupted 10–0 monofilament nylon suture. Postoperative protocol During follow-up examinations, CDVA was measured with an EDTRS chart and IOP was measured with a Goldmann applanation tonometer. All IOP measurements included in the analysis were taken between 8 and 10 am. The anterior chamber and fundus were examined. The postoperative course was analysed, including complications as well as the number of antiglaucoma medications. In the case of PC, gonioscopy was additionally carried out during each visit. In PDS, additional procedures were carried out when the IOP was elevated (≥16 mmHg) due to lack of filtration through the TDM or when there was a poorly developed or complete lack of a filtration bleb. Lack of filtration through the TDM or TDM insufficiency was diagnosed within the first 2 weeks after surgery, while healing processes did not yet restrict subconjunctival outflow and progressive IOP growth to above 16 mmHg. The presence of a bleb with subconjunctival outflow characteristics and the development of subconjunctival fibrosis were verified in a clinical study (engorged and tortous conjunctival vessels over the flap) and by means of Visante optical coherence tomography (OCT). Fibrosis diagnosis was made when the subconjunctival outflow was insufficient; the IOP increased and the bleb bacame flat or hyper-reflective, then

needling of the bleb was required. Goniopuncture, when required, was performed with an Nd:YAG laser. Three to 20 shots were applied using energy ranging from 2 to 4 mJ. Bleb fibrosis was treated with 5-fluorouracil (5FU) subconjunctival injections (0.2 ml, 5 mg) and needling, if required. Injections were made daily for five consecutive days or until the time when IOP normalization and fibrosis regression or stabilization in the Visante OCT test were observed, or complications associated with antimetabolite administration occurred. Suture lysis was performed during the first two postoperative weeks when poor filtration was present due to the watertight scleral flap. Success rates were analysed in two categories – complete and qualified. Complete surgical success was defined as IOP ≤ 18 mmHg with no antiglaucoma medications, and qualified success was defined as IOP ≤ 18 mmHg with or without medications. A procedure was considered to be a failure when IOP was > 18 mmHg with or without glaucoma medication, or when an eye required further glaucoma drainage surgery. On the day of surgery, glaucoma drugs were discontinued. When surgery was unsuccessful, medications were administered again in accordance with the guidelines of the European Glaucoma Society. Examinations were conducted before surgery on days 1 and 7, and 1, 3, 6, and 12 months after surgery. All patients received a topical steroid and antibiotic combination for four weeks after surgery.

Statistical analysis Statistical analysis of the investigated variables was performed with the Shapiro-Wilk χ2 test with corrections, the U Mann–Whitney test, and the Student's T-test. Friedman analysis of variance (ANOVA) for matched groups, mean ranks, and rank sums were also used for post-hoc comparison. The Kaplan-Meier method was used to calculate survival plots, and the differences were tested with the log-rank test. A P value of 0.05 or less was considered to be significant. Calculations were performed using the Statistica 10.0 PL program.

Results Twenty-nine patients underwent PC surgery, whereas thirty underwent PDS with the HealaFlow gel (Anteis Ophthalmology, Geneva, Switzerland). The mean follow-up was 12.7 ±0.3 months in the PC group and 12.6±0.3 months in the PDS group. Demographic data of both groups are summarised in Table 1.

Graefes Arch Clin Exp Ophthalmol Table 1

Patient demographic data

Group

PC

PDS

P*

Follow-up (months) n Age (years) Sex (female/male) Eye (right/left) Glaucoma type POAG PEX Pigmentary LOCS III scale (NC1/NC2) CDE AT

12.7±0.3 29 74.6±8.9 12/17 14/15 24 5 0 12/17

12.6±0.3 30 73.3±5.8 14/16 15/15 28 2 0 12/18

0.274 – 0.492 0.682 0.894 0.475

5.66±0.39 1.28±0.36

5.74±0.46 1.18±0.44

0.464 0.371

0.914

PC - phaco-canaloplasty group, PDS – phaco-deep sclerectomy group;* T - Student’s T-test or χ2 test; POAG - primary open angle glaucoma; PEX - pseudoexfoliation glaucoma; LOCS III – lens opacities classification system III; CDE - cumulative dissipated energy; AT - aspiration time (min)

no statistically significant differences in mean IOP between both analysed groups (P>0.05) (Fig. 1, Table 2). Medications Fewer medications were used after surgery than before the procedure in both groups (P<0.05). Preoperatively, the mean number of antiglaucoma medications in the PC group was 2.64±0.68, and this number decreased to 0.27±0.67 at the end of observation (χ2ANOVA =121.72, P<0.001; post hocmean ranks=3.02, sum ranks=78.5, P<0.05). Similarly, in the PDS patient group, the mean number of hypotensive medications was significantly reduced from 2.89±0.94 to 0.55 ±0.94 (χ2ANOVA =137.02, P<0.001; post hoc-mean ranks= 2.53, sum ranks=73.5, P<0.05). There were no statistically significant differences between the groups during the analysed period (P>0.05) (Table 3). At the end of the follow-up period, IOP≤18.0 mmHg without antiglaucoma medication was achieved in 76.0 % and 63.0 % of PC and PDS patients, respectively (χ2 =7.77, P= 0.005).

Intraocular pressure control Surgical success Preoperatively, the mean IOP in the PC group was 19.0 ±6.9 mmHg, and after 12 months of observation, it decreased by 33.0 % and was 12.6±2.7 mmHg (χ2ANOVA =33.77, P= 0.00001; post hoc-mean ranks = 2.61, sum ranks = 47.0, P<0.05). In the PDS group, the mean IOP decreased from the initial value of 19.1±5.8 mmHg to 14.3±3.5 mmHg, which is a 28.0 % reduction relative to the initial value. (χ2ANOVA = 48.35, P < 0.001; post hoc-mean ranks = 2.09, sum ranks=47.5, P<0.05). Throughout the study, there were

Fig. 1 Mean values, 95 % confidence interval (CI) for mean and standard deviations (SDs) in phaco-canaloplasty (PC) and phaco-deep sclerectomy (PDS) groups at specific times after surgery

The proportion of operated eyes meeting the 18 mmHg criterion for complete success after 12 months of follow-up was 79.0 % of the PC group and 76.9 % of the PDS group (P= 0.708). For the qualified success rate criterion, the proportions were 86.0 % and 84.3 %, respectively, (P=0.691). It should be noted, however, that the percentage of patients fulfilling the accepted criteria within the first six months after surgery in the case of the complete success rate and within the first

Graefes Arch Clin Exp Ophthalmol Table 2 Intraocular pressure (IOP) mean values, median values, standard deviations, and range in the phaco-canaloplasty (PC) and phaco-deep sclerectomy (PDS) groups at specific times after surgery

PC: phaco-canaloplasty group; PDS: phaco-deep sclerectomy group; SD: standard deviation; Pre-op: pre-operatively

Time

PC group Mean (SD)

PDS group Median

P

Range

Mean (SD)

Median

Range

Pre-op

19.0±6.9

18

10–41

19.1±5.8

18

12–36

0.829

1st day 7th day 1st month 3rd month 6th month 12th month

12.6±5.9 15.3±7.5 11.4±4.1 11.4±3.2 13.2±3.4 12.6±2.7

14 14 11 11 12 13

3–27 5–35 4–21 6–18 8–23 7–18

12.9±5.6 11.4±4.4 12.3±4.3 12.7±4.0 13.9±2.8 14.3±3.5

12 11.5 12 11 13.5 13

5–28 5–21 4–23 6–22 10–21 9–24

0.927 0.056 0.526 0.353 0.210 0.107

of the patients in the PC group. No change in CDVA was observed in 17.0 % of the PDS eyes and 16.5 % of the PC eyes.

three months in the case of the qualified success rate was greater in the PC group than in the PDS group. Stabilization was observed during subsequent observations with somewhat better results of the proportion of the PC group meeting the 18 mmHg criterion (Fig. 2).

Filtering bleb A filtering bleb was observed in 41.4 % of the PC group and in all cases of the PDS group on the first postoperative day (χ2 = 26.8, P<0.0001). Whereas, after 7 days it was present in 37.9 % and 100 % of the eyes, respectively (χ2 = 26.8, P<0.0001). Statistically significant differences were also noted at the one-month follow-up (χ2 =22.3, P<0.0001). A filtering bleb was seen in 27.5 % of the PC group and 93.3 % of the PDS group. Whereas, at the 6- and 12-month marks, the difference between both groups was no longer statistically significant (χ2 =3.1, P=0.079). Nonetheless, after both 6 and 12 months, it was seen more often in PDS (23.3 %) in comparison to PC (6.9 %). Neither the presence or absence of a filtering bleb affected the proportion of the groups that met the criterion for complete success with IOP≤18.0 mmHg. Complete success the in PC group after 12 months in the group with a filtering bleb was 73.3 %; however, when a bleb was absent, it was 81.7 % (P=0.067). Whereas, for the PDS group, it was 87.1 % with the bleb and 80.8 % without bleb (P=0.896) (Fig. 3).

Corrected distance visual acuity During the analysed period, the mean CDVA improved significantly in the PC group, from 0.74±0.70 to 0.11±0.17 log MAR (χ2ANOVA =87.48, P<0.001; post hoc-mean rank=2.74, sum rank=63.0, P<0.05) and from 0.57±0.45 to 0.11±0.16 log MAR in the PDS group (χ2ANOVA =59.65, P<0.001; post hoc-mean rank=2.56, sum rank=61.5, P<0.05). The mean CDVA improved in both groups for the first month after surgery and remained stable throughout the observation period. Only on the first postoperative day was there a statistically significant difference between the CDVA in both groups (P=0.001). At later follow up visits, no statistically significant differences were found (P>0.05) (Table 4). Improvement of one or more Snellen lines was present in 83.0 % of the PC group and 80.2 % of the PDS group. A decline of one line was noted in one patient after PDS (3.3 %), which was due to development of posterior capsule opacification (PCO) observed at the last follow-up, and there was no decline in any

Table 3 Mean values, median numbers, standard deviations, and ranges of medications used in phaco-canaloplasty (PC) and phaco-deep sclerectomy (PDS) groups at specific times after surgery

PC - phaco-canaloplasty group; PDS – phaco-deep sclerectomy group; SD: standard deviation; * U Mann–Whitney test

Time

PC group

PDS group

P*

Mean (SD)

Median

Range

Mean (SD)

Median

Range

Pre-op 1st day 7th day

2.64±0.68 0 0.18±0.94

3 0 0

2–4 – 0–5

2.89±0.94 0 0

3 0 0

1–4 – –

0. 326 – 0.823

1st month 3th month 6th month 12th month

0.04±0.19 0.04±0.19 0.22±0.58 0.27±0.67

0 0 0 0

0–1 0–1 0–2 0–3

0 0.07±0.37 0.24±0.69 0.55±0.94

0 0 0 0

– 0–2 0–3 0–4

0.823 1.000 0.967 0.304

Graefes Arch Clin Exp Ophthalmol Fig. 2 Cumulative proportion meeting the success criterion (Kaplan-Meier) of intraocular pressure less than or equal to 18 mmHg. a qualified success rate (log-rank test: 0.397, P=0.691). b complete success rate (log-rank test: 0.375, P=0.708). +/o surviving/non-surviving cases – PC group; +/o - surviving/nonsurviving cases – PDS group

Complications and additional procedures There was an intraoperative rupture and damage of the TDM in one eye of each group. In both cases, this was followed by postoperative iris incarceration in the TDM which required surgical reposition. The most frequent postoperative complication in the PC group was hyphema. This occurred due to blood reflux from distal outflow pathways of the aqueous humour into the anterior chamber. Hyphema with a blood layer was observed in 17 eyes (58.6 %), and microhyphema, defined as erythrocytes in the anterior chamber without a blood layer, was found in 10 eyes (34.5 %) All cases of hyphema resolved spontaneously within two weeks and no intervention was needed. Peripheral Descemet's membrane detachment was noted in one PC case, and it also resolved spontaneously. In the PDS group, bleb fibrosis was found in eight cases (26.7 %) (Table 5). To maintain the hypotensive effect of the surgery, additional procedures were performed in the case of PDS. Seventeen eyes

received 5-FU injections (56.6 %). The mean number of 5FU injections per patient was 3.7 and ranged from 1 to 10. Nd:YAG laser goniopuncture was performed in 17 eyes (56.6 %), suture lysis in 14 (46.7 %), and needling in 8 of the eyes operated on (26.7 %).

Discussion Apart from obvious differences resulting from the intubation of Schlemm’s canal, both surgeries technically belong to the group of non-penetrating procedures, in which proper dissection of the TDM is intended [11–15, 18, 20]. This particular step of the surgery seems to have a vital influence on the final hypotensive outcome. Moreover, in PC, the role of proper tension of Schlemm’s canal is emphasized [3]. In DS, however, additional procedures, which are performed postoperatively, seem to have a great influence on the final result.

Table 4 Mean values, median numbers, standard deviations, and ranges of corrected distance visual acuity (log MAR - CDVA) in phaco-canaloplasty (PC) and phaco-deep sclerectomy (PDS) groups at specific times after surgery Time

Pre-op 1st day 7th day 1st month 3th month 6th month 12th month

PC group

PDS group

P*

Mean (SD)

Median

Range

Mean (SD)

Median

Range

0.74±0.70 2.14±2.24 0.71±1.23 0.29±0.35 0.10±0.17 0.13±0.21 0.11±0.17

0.69 0.91 0.46 0.22 0 0 0

0–2.53 0–6.21 0–6.21 0–1.61 0–0.46 0–0.69 0–0.46

0.57±0.45 0.55±0.40 0.46±0.48 0.39±0.26 0.14±0.20 0.11±0.19 0.11±0.16

0.51 0.46 0.46 0.34 0 0 0

0–1.61 0.11–1.61 0–1.83 0–1.13 0–0.69 0–0.69 0–0.46

PC- phaco-canaloplasty group; PDS – phaco-deep sclerectomy group; SD: standard deviation; * U Mann–Whitney test

0.507 0.001 0.631 0.081 0.758 0.878 0.779

Graefes Arch Clin Exp Ophthalmol Fig. 3 Cumulative proportion meeting the complete success criterion (Kaplan-Meier) of intraocular pressure less than or equal to 18 mmHg with and without a filtering bleb. a PC group (log-rank test; −1.829, P= 0.067) b PDS group (log-rank test; 0.131; P=0.896). +/o surviving/non-surviving cases

These procedures are 5-FU subconjuntival injections, goniopuncture, suture lysis, or needling [21]. Nd:YAG laser goniopuncture can also be performed on eyes after PC, but it was not carried out in our PC group, which is in line with the 12-month results of multicenter trials [4, 5, 7, 22]. On the other hand, goniopuncture was performed in 17 PDS patients (56.6 %) together with suture lysis and 5-FU injections. The rate of goniopuncture in canaloplasty or viscocanalostomy differs vastly in the literature and is given between 0 % to 18 % of cases and 10–70 % in PDS cases [5, 9, 23]. IOPs were controlled well in both groups. In the PC group, IOP values at the 12-month follow-up were 12.6±2.7 mmHg Table 5

Postoperative complications

Complications

PC group n (%)

PDS group n (%)

P*

1 (3.4)

1 (3.3)

0.981

Intraoperative TDM rupture Postoperative Hyphema blood level in AC erytrocytes in AC Descemet membrane detachment Anterior chamber cells Hypotony until 7 days until 30 days

17 (58.6) 10 (34.5) 1 (3.4)

– – –

– – 0.313

2 (6.9) 8 (27.6) 5 (17.0)

1 (3.4) 9 (30) 3 (10.0)

0.554 0.879 0.477

until 180 days Choroid detachment Bleb fibrosis Iris incarceration

– 2 (6.9) – 1 (3.4)

– – 8 (26.7) 1 (3.3)

– 0.157 0.034 0.981

PC - phaco-canaloplasty group; PDS – phaco-deep sclerectomy group; TDM - trabeculo Descemet’s membrane; * χ2 test

on 0.27 ±0.67 medications, and in the PDS group, 14.3 ±3.5 mmHg on 0.55±0.94 medications (P>0.05). The results of this study are comparable to the results of these procedures previously published separately [5, 9, 24–27]. However, differences mainly due to the varying mechanisms of both procedures should be emphasized. Mean IOPs were higher in PC cases on the first week of follow-up, and the difference relative to PDS neared statistical significance (P=0.056, Table 2). On further follow-up, mean IOPs were lower in PC patients than in PDS patients. By analysing the Kaplan-Meier survival plots for the PC group, it can be noted that, during the initial period after the operation, a smaller percentage of the group reached the IOP level according to the adopted criterion, and this situation was reversed in further follow-ups. The ease of outflow in DS through the subconjunctival pathway may contribute to differences in early postoperative IOP. The outflow functions right after surgery, whereas, in studies on human and bovine eyes in PC, it may take more time for the conventional pathway to adjust to a newly dilated Schlemm’s canal, especially when the lumen of the canal is collapsed and the ostia of collector channels are closed [11, 20, 28]. The filtering bleb was present more often in DS than in PC, not only in the first week, but also after a month. At the end of the observation period, a filtering bleb was found more frequently in PDS than in PC patients; however, the difference was not statistically significant. It should be noted that despite the similarity of Kaplan-Meier plots in the PC and PDS groups, there is a difference in success in eyes where a filtering bleb is present or absent. In PC patients, the absence of a bleb and the presence of a bleb in PDS patients means IOP stabilization in a higher proportion of subjects (Fig. 3). Shingelton et al. noted 3 blebs out of 54 operated eyes, while Grieshaber et al. observed 4 blebs out of 32 patients at the 12-month follow-up [5, 9, 29]. This may be the reason why some canaloplasty patients

Graefes Arch Clin Exp Ophthalmol

require the administration of hypotensive treatment during the early postoperative period, which is often discontinued later [6]. On the other hand, the main causes of decreased efficacy later in the observation period were bleb fibrosis (8 eyes, 27 % of PDS) and insufficiency of the TDM, which was the reason for performing goniopunctures [30]. Correctt patient selection seems to be a very important factor for the success of glaucoma surgery. Moreover, nowadays, surgeons pay attention to dry eye symptoms, the length of previous topical hypotensive therapy, and the correlation of these two factors with the postoperative result [31]. Although such factors seem to be of great importance in DS, in canaloplasty, attention should be paid to the physiological aspects of Schlemm’s canal. Poor blood reflux and an IOP≥ 30 mmHg that lasts for a longer period of time are indicative of the morphological status of the collector channels and Schlemm’s canal [32]. However, in our experience, it is not always possible to discern blood reflux before surgery, even in eyes that have good results after canaloplasty. Verification of the qualification process for the operation often occurs after surgery in PC case. In many cases, an intraoperative or early postoperative decrease of IOP leads to blood reflux into the anterior chamber from distal outflow pathways. This phenomenon explains the occurrence of hyphema. Grieshaber et al. consider hyphema as a positive prognostic factor rather than a complication [33]. On the other hand, Lewis et al. suggest this effect may be enhanced when Schlemm’s canal is left under higher tension [3]. We noted a higher incidence of hyphema than other authors in the studied PC cohort. 58.6 % of patients in the PC group had hyphema, and 34.5 % had microhyphema, defined as blood that does not form a layer in the anterior chamber. Bull et al. found hyphema in 5.5 % and microhyphema in 12.8 % of operated eyes, while Lewis et al. noted the presence of hyphema in only 3.2 % of cases [3, 4]. In our group, which is in line with other results, hyphemas resolved spontaneously, most often within two weeks. In summary, safety and efficacy profiles are similar for both procedures. There are no statistically significant differences between the groups in terms of mean IOP, the number of required postoperative antiglaucoma medications, CDVA, or severe complication rates. However, PC patients required no postoperative management, which means that a hypotensive effect was achieved solely during surgery. Whereas in PDS, the mean IOP was reached with the help of additional postoperative interventions in about half of cases. Also, although not statistically significant, the PC group required fewer medications, demonstrating a tighter SD and more patients without medications (P=0.005). Nonetheless, results should be confirmed by a number of comparative studies or clinical trials allowing for additional statistical inferences based on a longer period of observation.

Acknowledgments The authors have no proprietary interest in any of the materials, products, or methods mentioned in this article. No financial support was received for this submission. This paper was presented in part at the 5th World Glaucoma Congress in Vancouver.

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