4 a new low cost glaucoma surgical technique

Scorolli Sclerectocanalotomy A new low-cost glaucoma surgical technique AUTHORS Lucia Scorolli1-2, Enrico Meduri4, Renato P. Meduri5, Paola Adami1, Alessandro Meduri6, Claudio Melloni1, Marialuisa Lugaresi2, Sergio Z. Scalinci2-3.

1 St. Lucia High Private Hospital, Bologna, Italy 2Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Italy 3Glaucoma and Low Vision Study Center, Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy 4MS, Sofia University, Sofia, Bulgaria 5IE Business School, Madrid, Spain 6Department of Surgical Specialities, Ophthalmology Clinic, University of Messina, Italy Corresponding author: Lucia Scorolli St. Lucia High Private Hospital, Bologna, Italy VIA MURRI 164, 40137 Bologna, ITALY Phone +39. 051440822

Fax +39. 051443106

E-mail luciascorolli@yahoo.it ABSTRACT AIM OF THE STUDY: the purpose of this prospective, randomized and blinded study was to value the efficacy of “Scorolli Sclerectocanalotomy”, a new low-cost glaucoma surgical technique (compared to a classical technique of deep sclerectomy).

MATERIALS AND METHODS: 110 pseudophakic eyes (group A) in 110 patients, 45 phakic eyes (group C) in 45 patients, all of them resistant to maximal (3 active principles, each of them used 3 times /day) medications or/and previous filtering surgeries. Each patient was treated with “Scorolli Sclerectocanalotomy” and was followed for 1.8 year; 70 eyes in 70 patients (group B) were the control group, each of them treated with deep sclerectomy adding T-flux valve or Aquaflow type plant collagen.

Authors evaluated average age, preoperative and postoperative intraocular pressure (IOP) for 1.8 year; preoperative and postoperative

Humphrey computerized visual field after 1.8 year; preoperative and 1.8 year-postoperative best-corrected visual acuity.

RESULTS: Authors defined success IOP ≤21 mm Hg with or without therapy (with at least 20% IOP reduction from the baseline) and distinguished the success in: A) partial success as an IOP ≤ 21 mm Hg B) good success as an IOP ≤ 18 mm Hg with C) exceptional success IOP ≤ 15 mm Hg. Visual field scores are statistically significantly and are different from preoperative conditions. Best Corrected Visual scores did not experience significant changes.

There was no use of intraoperative antimetabolite such as mitomycin C (MMC) or 5-Fluorouracil (5-FU) was confirmed. Finally cases and controls were paired by sex and post-operative period.

CONCLUSION: “Scorolli Sclerectocanalotomy” combines simplicity and low costs with the absence of

postoperative inflammation in the anterior chamber as well as in the developed cataract and the flat bleb. No choroidal detachment was observed and there was also strong reduction of IOP that is also adjustable in the long term.

KEYWORDS: Sclerectocanalotomy, Low-cost surgery, Deep sclerectomy, Canalectomy, Glaucoma surgery.

INTRODUCTION Deep sclerectomy1 is a non-penetrating filtering surgery used in the surgical treatment of open angle glaucoma uncontrolled by medical therapy. It aims to reduce the complications of classic trabeculectomy (hyphema, inflammation of the anterior chamber, excessive filtration leading to hypotonia, reduced or abolished anterior chamber, choroidal detachment and endophthalmitis). The filtration of aqueous humor from the anterior chamber to the subconjunctival space takes place through a thin trabecular Descement’s membrane2, which represents the anterior and posterior trabecular meshwork at 1 mm from the limbal margin of Descemet's membrane. This membrane has a resistance to outflow of the aqueous humor that is moderate but constant and reproducible, avoiding the sharp drop of intraocular pressure, which is observed during a trabeculectomy. The aqueous humor flows to the draft of the subconjunctival filtration and eventually into Schlemm's canal and into the intrascleral aqueous veins1-3-4-5. However, often there exists a reduction of filtration due to fibroblast proliferation that has led to the use of multiple resorbable scleral and other implants, of difficult application technique, and of high cost, of which the most common are evaluated in this work. The quantity of flowing aqueous humor increases also in the case that there is an opening of the external wall of Schlemm’s canal, facilitating the flow through the 30/40 collecting canals (canalectomy).

MATERIALS AND METHODS This study was a prospective, randomized, blinded study performed to evaluate the efficacy of a personal modification of deep sclerectomy, which we call “Scorolli Sclerectocanalotomy”, using only low cost materials. This technique makes it possible to keep the scleral space open and to maintain the posterior deflux of aqueous humor constant without having flat anterior chamber and/or choroidal detachment. The whole procedure is performed using only a thread of nylon 10/0 that replaces the function of the intrascleral

installations at a much lower price .The study was initially developed in pseudophakic eyes resistant to therapy and other filtering surgeries, and later extended to phakic patients resistant to maximal medications6 and with particularly high IOP (Intra Ocular Pressure) and very compromised visual fields.

Inclusion criteria: Patients in maximum topical therapy (3 active chemical principles, 3 times per day) for almost 18 years with an IOP> 21 mmHg and resistant to many surgeries; control group composed by patients with same problems but who received a deep sclerectomy plus AIDS. Neither group used mitomicine C (MMC) or Fluorouracil (5-FU) 7.

Exclusion criteria: Type 1 diabetes patients in therapy for less than 18 years and patients with IOP < 21 mmHg. Steps to be performed in the "Scorolli Sclerectocanalotomy" [Figure 1-2]: Step 0: The instillation of one drop of pilocarpine 2% 15 minutes before surgery administered as well as one drop of povidone-iodine 5 minutes before the surgery.

Step 1: The anesthesia is performed directly in the operating room with carbocaine without adrenaline in upper subtenonian location. The use of diathermy is variable but always contained in order to avoid scarring consequences that can favor the adhesion between the tissues. Always wash with cold physiologic solution in order to reduce the bleeding.

Step 2: Perform a flap of the conjunctiva and of Tenon's capsule, limbus-based, about 10-12 mm long, at about 15 mm from the limbus without making any incision on either side of the flap (the length of the flap allows to converge the conjunctiva and the capsule satisfactorily without lateral incisions that may increase the risk of excessive fibroblastic scarring on the sides of the filtration).

Step 3: Fold towards the cornea the conjunctival flap, which may be retained and folded by an 8/0 Vicryl thread, held with a Kocher clamp. Perform a limbusbased scleral cover for approximately 5x5 mm for 1/3 of the thickness of the scleral surface. The dissection of the superficial flap is pushed anteriorly towards the sclero-corneal limbus up to 1 mm after the surgical limbus.

Step 4: Perform a second limbus-based scleral flap on the bed of the previous one, characterized by a thickness such that it almost arrives at Bruch’s lamina.

The flap may be of various shapes, but the easiest one to perform is a trapezium one; a minimal size of 2x3mm is sufficient.

Step 5: The advance of the second flap must arrive to the cornea up to the base of the first scleral flap on the subjunctive bed; this is then removed with Vännäs’ scissors.

Step 6: After having dissected the anterior sclerocorneal region and visualized the outer wall of Schlemm's canal, slice it so that the fibres are visible at high magnification using a gripper anatomical type of binding McPherson forceps. At this point we can visualize a small exudation of aqueous humor through the thin Descemet's membrane and trabecular bone.

Step 7: Push the needle of the 10/0 nylon thread into the outer scleral portion of the first and second flap; at this point we get to include some fibres of the outer and inner wall of Sclhemm canal, come out and tie it at the rear of the scleral bed. The two ends of the thread are knotted with the technique of the 3+2 and the margins are cut as short as possible to close to the knot.

The same operation is repeated on the upper-outer edge of the other side.

Step 8(optional): If the pressure is rather high, we can add between these two points a middle one that takes the wall of the canal and goes in the mid wall of the deep bed, seeking additional space for posterior filtration.

of the iris, we suggest the placement of one milliliter of Carbachol 10mg below the closed flap: the iris will retract instantly and the spaces will remain free.

Step 11: Always check that at the end of the surgery the pupil is miotic and regular. If it is slightly irregular in the superior part, stretch the iris by inserting a fixed 12.7 mm insulin needle in the superior clear cornea on the temporal side. Resistance will never be encountered. The patients must be discharged with a tight pupil but without pilocarpine drops.

Samples and study groups All subjects were informed at the attendance policy of this sperimental study, about the kind of surgery and of the possible consequences; therefore they could give their consensus signing the Declaration of Helsinki.

Starting from 1 October 2010 we performed a prospective study on 110 eyes of 110 patients treated with posterior “Scorolli Sclerectocanalotomy” (group A) suffering from chronic simple open-angle glaucoma in advanced and sub-terminal stages, all pseudophakic.

As a prospective control group we used 70 eyes (selected randomly) treated with deep sclerectomy (group B) with T-flux valve or with Aquaflow type plant collagene8-9 (40 eyes were the second eye of the patients of group A and 30 eyes of new patients. All were pseudophacic eyes). We also performed surgery on 45 phakic patients starting from October 2011 (group C). All patients were followed continuously and constantly from the beginning of the treatment up to 1.8 year after treatment.

Age and race of patients

Step 9: Replace the superficial scleral flap, suture the two ends of the outer flap with the same 10/0 nylon thread in the superior-posterior right and left angles.

Thus, there are two sutures of the outer flap.

Step 10: The next step is the suture of the capsule and of the conjunctiva. These can be performed in the same step taking both the capsule and the conjunctiva with an 8/0 Vicryl thread, or in two different steps: first suture the capsule and then the conjunctiva, both with a continuous suture with an 8/0 Vicryl. The suture is performed tightening every stitch after having passed it inside the previous one so that each stitch is pointed like a knot. The resistance of the capsule-conjunctival layer must be perfect. If we notice that there is too much space between one stitch and another on the conjunctiva, we can add separate stitches between the points. If, while we are separating the walls of Schlemm’s canal, we have a light slipping at the basis

The average age of group A was 70 ± 5.5. ds The average age of group B was 70.5 ± 8.0. ds The average age of group C was 70.7 ± 3.0. ds Ultimately we treated 41% females and 59% males, with gender equality in the three groups.

As regards the semiological derivation the groups were as follows: Group A: 100 (90.9%) Caucasian patients; 3 (2.74%) Black patients; 7 (6.36%) Asiatic patients.

Group B: 48 (68.57%) Caucasian patients; 10 (14.28%) Black patients; 12 (17.15%) Asiatic patients.

Group C: all patients were Caucasians Preoperative intraocular pressure (assessed the day before the surgery) A standard custom of our working group is to instill 3 drops of Oxybuprocaine Hydrochloride (Novesina ®, Novartis, 4mg) within 20 second of each other, in order to have the best measurement of IOP in all adult and collaborating with a single standardized patient procedure. This system allows the alteration of the value of IOP to be reduced as a result of repeated measurements and therefore, of a bad sampling of the data pre-and post-operatively. IOP was measured with a Goldman tonometer using fluorescein10 or Reichert Tono-Pen Avia®.

•The average preoperative IOP with maximal medications (3 times a day, 3 actival principles), in group A, was 24 ± 3.5mmHg •The average preoperative IOP with maximal medications in group B was 23.78 ± 4.2 mmHg •The average preoperative IOP with maximal medications in group C was 24.5 ± 2.9 mmHg Humphrey computerized visual field (assessed 3 days before the surgery) •For group A the average MD was -15.24 ± 1.79 and the average PSD was 9.12 ± 1.63; •For group B the average MD was -15.12 ± 1.89 and the average PSD was 9.00 ± 1.24; •For group C the average MD was -14.93 ± 1.69 and the average PSD was 9.24 ± 1.02.

Visual acuity (Assessed 3 days before the surgery) The visual acuity was measured with the EDTRS method11 for distance vision and the Eduard von Jaeger method for near vision.

•The average visual acuity for group A was 0.19 ± 0.9 LogMAR with best correction (BCVA) for distance, and Jaeger-1 with best correction for near.

•The average BCVA for group B was 0.08 ± 1 LogMAR for distance, and Jaeger-1 with best correction for near.

•The average BCVA for group C was 0.05 ± 1.5 LogMAR for distance, and Jaeger-1 with best correction for near.

Basically in the preoperative it is evident as no statistically significant difference is present between various groups for age, sex, MD, PSD, PIO ( p=0.055 to Kruskal-Wallis Test).

Preoperative PIO between various groups is : 

Group 1 and 2 p=0,923



Group 1 and 3 p=0,014



Group 2 and 3 p=0,064

[Figure 3]

Follow-up (1 year) IOP was examined on the following days after surgery: the day after, 3 days after, 7 days after, 10 days after, 17 days after, 21 days after, 28 days after, 35 days after, 42 days after, 49 days after, 64 days after, 79 days after, 94 days after, 119 days after, 135 days after, 165 days after, 180 days after, 210 days after, 242 days after, 272 days after, 300 days after, 365 days after, 455 days after, 545 days after, 570 days after, and 608 days after.

Statistical analysis At first the global data was examined using the Shapiro-Wilk test in order to establish the eventual conformity to a normal distribution. After finding incompatibility with this distribution, the values were considered to be nonparametric. Therefore, they were analyzed using nonparametric methods for the analysis of variance (Kruskall-Wallis test), Mann-Whitney Test and Friedman test. A comparison of the data before and after the treatment was performed using the Wilcoxon test. A p value less than 0.05 was considered statistically significant. The statistical analyses were performed using the SPSS 13.0 software package (SPSS Inc., Chicago, IL, USA). We used "KaplanMeier survival curve"12 and "Log-rank" test to see the trend of IOP and visual acuity over time, as stated by American Glaucoma Society: "Survival curves (Kaplan-Meier) are considered mandatory for demonstrating surgical success"13. In order for the study to be statistically sound, the following need to be statistically tested:

We also need to understand whether the difference between the three groups is statistically significant: if this was not the case, we would conclude that the difference we record between these samples is randomly generated and sample dependent: there would be no actual difference between the populations and our study would lose relevance. Specifically, we are interested in the difference between Group A (those treated with the Scorolli technique) and Group B (deep sclerectomy with T-flux valve). [Figure 4]

The analysis of variance, showed a p = 0.000 (statistically significant), demonstrating differences between the data of groups A, B and C. In order to apply the Mann-Whitney Test, the preoperative values of groups A and B showed a p = 0.222 (not statistically significant), demonstrating no particular differences between the two groups. Instead postoperative values between the groups A and B, showed a p = 0.000 (high statistical significance). The pre- and postoperative values between groups A and C showed a p = 0.000 (statistically significant), demonstrating a deviation between them. Except the 21th postoperative day that showed a p = 0.092, where the values were less different between the two groups. The p proved to be statistically significant in all measurements (p = 0.000) in groups B and C. Expect the 1st postoperative day that showed a p = 0.673 (no statistically significant).

The Kaplan-Meier curves and Log-rank test showed a p <0.001 and a bigger consistency of the results of group A than the others groups [Figures 6].

RESULTS

Humphrey Computerized Visual Field

Postoperative intraocular pressure

The results 608 days after were as follows:

The authors consider the surgery a success if the IOP ≤ 21 mmHg without medication, with at least 20% IOP reduction from baseline. We consider the surgery a complete success if the IOP ≤ 18 mmHg without medication or ≤15 mmHg with or without medications (maximum two medications with one active principle).

We consider the surgery a failure if IOP >21 mmHg with or without medication (independently from the number) in the 1.8 year following surgery. 608 days after surgery, obtained pressure values were the following:

For group A the average MD was -14.59 ±2.11 and the average PSD was 8.97 ± 1.43;

•The difference between the preoperative and postoperative values for each group •The difference between groups The differences between preoperative and postoperative values need to be tested for statistical significance in order to understand the effectiveness of the surgery in changing the medical condition of the patient.

•The average postoperative IOP with maximal medications in group A was 11.7 ± 3.2 mmHg •The average postoperative IOP with maximal medications in group B was 13.00 ± 3.5 mmHg •The average postoperative IOP with maximal medications in group C was 15.09 ± 2.2 mmHg. In the summary we can say that a 1.8 year after surgery, pressure reduction was: ●

51.04 % nel Gruppo A

●

21.55 % nel Gruppo B

●

38.4 % nel Gruppo C [Figure 5]

For group B the average MD was -14.00 ±1.76 and the average PSD was 8.87 ± 1.49; For group C the average MD was -13.12 ± 1.88 and the average PSD was 8.17 ± 0.66 [Figure 7].

Group A shows a p=0.000(statistically significant) for pre and postoperative performances of both MD and PSD. That demonstrates a clear difference between the pre-and post-operative performance of the MD and PSD. Group B shows a p=0.000(statistically significant) for pre and postoperative performances of MD. The pre and postoperative performances of PSD show a p=0.804(no statistically significant). Group C shows a p=0.003(statistically significant) for pre and postoperative performances of MD. The pre and postoperative performances of PSD show a p=0.289(no statistically significant). The confrontation between various groups and groups in pairs shows a strong significance, with values of p = 0.000, in both pre and postoperative period (A vs. B, B vs. C, A vs. C) of MD and PSD. Therefore large differences emerge between the values of the different groups.

Visual acuity 7days, 180 days and 608 days after surgery, obtained BCVA values were the following: Visual acuity was

measured using the EDTRS method for distance vision and the Eduard von Jaeger method for near vision.

postoperative. The incidence of complications in our 3 groups is summarized in table 1. [Table 1]

•The average BCVA for group A was 20/38; 20/31; 20/31 for distance, and 0.28± 0.8; 0.19 ± 0.9; 0.19 ± 0.9 LogMAR with best correction for near.

After surgical techniques, no patient required further surgery within the 1.8 year. 20% of patients in group B required use of medical therapy after surgery. 14% of patients in group A required use of medical therapy after surgery. 10% of patients in group C required use of medical therapy after surgery. These patients were treated with 1 instillation of anti-prostaglandin medications per day, starting by the 156th day. [Figure 9: Table1]

•The average BCVA for group B was 20/100; 20/25; 20/25 for distance, and 0.70± 1.4; 0.09 ± 0.9; 0.10 ± 0.8 LogMAR with best correction for near.

•The average BCVA for group C was 20/38; 20/23; 20/26 for distance, and 0.28± 1; 0.06 ± 0.9; 0.11 ± 0.8 LogMAR with best correction for near.

608 days after surgery, obtained BCVA values were the following: Visual acuity was measured using the EDTRS method for distance vision and the Eduard von Jaeger method for near vision.

•The average BCVA for group A was 20/25; 20/32 and 0.19 ± 0.9 LogMAR for distance, and Jaeger-1 with best correction for near.

•The average BCVA for group B was 20/25 and 0.10 ± 0.8 LogMAR for distance, and Jaeger-1 with best correction for near.

•The average BCVA for group C was 20/25 and 0.11 ± 0.8 LogMAR for distance, and Jaeger-1 with best correction for near [Figure 8].

The analysis of variance between the three groups, showed a p = 0.000, in both pre-and postoperative.

This shows a lack of homogeneity in the recorded values. In 7th day there was a bigger homogeneity in the results, between group A and C (p = 0.441). In 365th day there was a bigger homogeneity in the results, between the group B and C (p = 0.618). The remaining comparisons show an evident discrepancy between the data of the various groups. The Wilcoxon test showed a discrete stability in the values of group A between the pre-and postoperative (p = 0.614) and in group B (p = 0.601). Group C showed a bigger difference between pre-and postoperative (p = 0.000).

The Kaplan-Meier curve showed a higher stability on the group A and C, compared to group B (p <0.001).

Complications The complications were divided into 3 types: perioperative, early postoperative and late

DISCUSSION Non-penetrating deep sclerectomy was designed for primary and secondary open-angle glaucoma. The main problems of hypo and hyper filtration can be avoided with this technique because it optimizes the ability of the trabecular Descemet’s membrane to modulate the outflow of aqueous humor. The mechanism regulating the re-absorption of aqueous humor has not yet been entirely clarified. According to a study by Chiou, Mermoud, Underdahl et al (1998)14, the aqueous humor passes through the membrane and fills the scleral space; it is then reabsorbed through the formation of a filtering bleb, but probably also through Schlemm’s canal, the intrascleral aqueous veins, and the sub-choroidal space. With regard to Schlemm’s canal, our technique leads to a better flow of the aqueous humor due to the creation of spaces on Schlemm’s external wall; this is the case because the 10/0 nylon thread is also passing through different parts of the external-internal wall. With the advantages described below, this represents an additional positive aspect of “Scorolli Sclerectocanalotomy” because the IOP is manageable with time, even in the long term. In fact, using a slit lamp and introducing a 30 Gauge needle it is possible to perform the following: •Reach the posterior flap below the conjunctiva and cut it on both sides (1% group A; 2 times, 2% group C; 1 time); •Find the border of the flap, pass below it and cut the central or peripheral nylon thread (1% group A; 1 time, 1% group C; 1 time); •Penetrate in the anterior chamber, thus transforming the surgery into a full penetrating one, avoiding however the typical complications because the outflow is always soft. (2% group A; 1 time, 1% group A; 2 times)

Another main advantage of not opening the anterior chamber is to significantly reduce postoperative inflammation in the anterior chamber. This could also substantially reduce the risk of endophthalmitis originating from the bleb. The evaluation of the mean cape disk and nerve fibers (oct optic nerve) was not taken into consideration, since the aim of our work was to evaluate if this technique was able to reduce the pressure in an effective and lasting way. The advantage of not using of MMC (Mitomycin) or 5-FU (5fluorouracil) on any of our patients is that they are known to be potent inhibitors of collagen synthesis by fibroblasts15. This is due to fact that both are able to increase the success rate in eye filtration surgery patients who have undergone a previous surgery as well as in those high-risk patients and thereby, in our opinion, distort the good results. Work involving new surgical techniques and the simultaneous use of these antimetabolites should be carefully considered and studied16.

•It is particularly recommended in pseudophakic eyes who have higher risks of choroidal detachment , and it is applicable to all eyes that have already been operated on in a first operation;

Statistical analysis confirming that the surgery has a statistically positive effect on the medical condition of the patients, and that the IOP and the visual field are different between each group and between pre and post-operative conditions.

•It is necessary to evaluate the patient very often, with the following timeframe: 3 times per week during the first week, 1 time per week during the following two months in order to follow the healing

The results show that the differences in IOP and Visual Field values (both MD and PSD) across the three samples are statistically significant; best corrected Visual Acuity however is not affected by the sample difference, since the difference between the three samples is not statistically significant (at the 99% confidence level).

Advantages of "Scorolli Sclerectocanalotomy": The technique requires a learning curve slightly longer than the one for the drill Trabeculectomy17, but it has numerous advantages: •The anterior chamber does not disappear; •The location of the suture is posterior to such a degree that it does not interfere in the ocular motility and it produces no pain; •The bleb that is created is always flat, never too visible, and it does not generate a feeling of foreign body; •Choroidal detachment is very rare, hardly ever present; •The operation can be performed on an outpatient basis as cataract surgery;

Compared with deep sclerectomy: •This surgery involves a very limited cost (an average of €60 vs an average of €500 for the insertion of valves). The necessary equipment is represented by: a surgical microscope, one eyelid speculum, one syringe with carbocaine, one diathermy instrument or a disposable cautery, one 10/0 nylon wire, one 8/0 Vicryl wire (which can be used both to fold the subjunctive– capsular strip and to suture the capsule and the conjunctiva), one diamond scalpel (preferable; however, a 30° disposable scalpel is sufficient), one disposable bevel-up, possibly one vial of Carbachol, and an antibiotic ointment for the medication.

Disadvantages:

•The learning curve is less than the introduction of collagen implants but equivalent to a T-flux introduction.

In conclusion, deep “Scorolli Sclerectocanalotomy” is a new non-penetrating surgical technique that allows a safe and effective reduction of the IOP. The remaining trabecular Descemet’s membrane ensures a progressive reduction of the IOP and these increases the safety of filtering surgery without opening the anterior chamber.

More studies are needed both to verify the percentage of long-term success of this technique and to exactly understand the dynamics of the constant filtration mechanism.

The current results are extremely encouraging. Group A, B and C, show statistically different results, with group A appearing to be a better medical choice especially much more cost-efficient. These considerations provide the basis for incredibly favorable perspectives in developing countries, where the economic factor is a constant problem, but also in the developed world, where the global economic downturn is imposing strict cost rationalizations in many countries. This would be achieved while also enjoying the advantages of a filtering surgery in which the anterior chamber is not opened and without the onset of cataract.

In conclusion, the benefits are similar to deep sclerectomy and AIDS but costs are lower.

Declaration of interest

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Demeter S, Hailey D. “Non-penetrating glaucoma surgery using AquaFlow™ collagen implants”. Issues in Emerging Health Technologies, Aug 2011, (22):1-4.

The authors report no conflicts of interest or financial support. The authors alone are responsible for the content and writing of the paper.

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Fingeret M, Casser L, Woodcome HT. “Atlante di tecniche fondamentali di diagnosi e terapia oculare”. Medical Books 1992.

Ethical Approval

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Figure legends:

15mmHg. The curve is supported by a p <0.001(statistically significant).

Figure 1-2: Figure 5: Step 1-2: Conjunctiva and Tenon’s capsule flap, limbus based, 10-12 long, 15mm from the limbus;

The complessive reduction of IOP in the 1,8 year after surgey in the group A, B and C.

Step 3: Conjunctival flap folded by a 8/0 Vicryl thread; Figure 6: Step 4: Limbus base scleral cover 5x5 mm, 1/3 mm thickness pushed up to 1mm after the surgical limbus; Step 5: Second Limbus 3x2 Scleral flap, thickness almost at Brunch’s lamina, advanced to the cornea on the subjunctive bed Step 6-7: Second flap removed; Step 8: Outer wall of Schlemm’s canal. Push the needle of the 10/0 nylon thread in the outer scleral portion of the first and second flap, including fibres of the outer and inner wall. Tie the thread at the rear of the scleral bed; Step 9-10-11: Same operation repeated on the upperouter edge of the other side; for very high pre-op pressure, add one point in the middle for additional space; replace the superficial scleral flap, suturing the two ends of the outer flap with the same 10/0 nylon thread. The final step is the suture of the capsule and of the conjunctiva taking both of them with a 8/0 Vicryl thread or in two different steps with a continuous suture. The suture is performed tightening every stitch after having passed it inside the previous one so that each stitch is pointed like a knot; If separating the fibers of the Schlemm’s walls we have a slipping of the iris base, place 1mm of Carbachol 10mg below the closed flap. At the end of the surgery check the pupil: it has to be always miotic and regular;

Average Pre and Postoperative IOP (mmHg), we consider complete success an IOP≤15mmHg without medication, and a failure an IOP>18mmHg with or without medication. discriminating success from failure is equal to 15mmHg. The curve is supported by a p <0.001(statistically significant).

Figure 7: Average Pre and Postoperative MD and PSD (dB) measured with Humphrey computerized Visual Field in all groups.

Figure 8: Average Pre and Postoperative Visual Acuity measured with Eduard Jaeger method for near vision in LogMAR. The strong decrease is clearly shown in the first few postoperative days of group B, typical course of a trabeculectomy. The curve shows an initial peak in the stability of visual acuity for all examined groups in the first postoperative days, especially for group B. They then settle and reach a plateau until the end of our follow-up. Is also evident the increased stability of visual acuity of group A. The cut-off value is equivalent to the loss of two lines of optotype compared to preoperative values of visual acuity. Even in this case, the curve assumes statistical significance, with a p <0.001.

If you are not satisfied of IOP the day after, insert a fixed 12.7 mm insulin needle on the temporal side of the flap, stretching one of the threads.

Figure 9:

Figure 3:

Table1: Surgery complications divided in preoperative, early post-operative and late post-operative in all groups.

The different statistics of the baseline Figure 10: Figure 4: From the graph it is evident that the group A maintains the same values of IOP over time. Likewise it is clear that the group B has a lower continuity of pressure values, documenting an increase of IOP already from the first postoperative days. The cut-off value discriminating success from failure is equal to

Table 4484: Poster presented at the ARVO Annual Meeting Washington State Convention Center Seattle, Washinton, 5-9 May 2013 “A New Technique for Glaucoma Surgery: Scorolli trabeculectomy”.