Following Patients After Selective and Pascal Laser Trabeculoplasty for Treatment of Chronic Open-Angle Glaucoma

Selective laser trabeculoplasty (SLT) and pattern laser trabeculoplasty (PLT, a novel computer-guided laser that is being using to treat open-angle glaucoma) are two laser surgery methods to make a trabeculoplasty on patients with open angle glaucoma. An observational prospective study will be performed, a consecutive convenience sample patients with indication for SLT or PLT will be recruited during June 2014 to uly 2016 and follow-up until 6 months, at the Fundación Oftalmológica Nacional (Bogotá-Colombia). A non-probabilistic convenience sampling is performed, considering that the average number of patients diagnosed with chronic open-angle glaucoma undergoing to Laser trabeculoplasty at the Oftalmológica Nacional Fundacion corresponds to approximate 2 per month. Therefore it is expected to enroll one patient per month for each of the laser used (SLT and PLT) for trabeculoplasty. Finally obtaining a sample size of 18 patients per type of laser for a total of 36 patients in the recruitment period, between September 2014 and July 2016.

This study is strictly observational, that's why the laser procedure is covered by the national health insurance of each patient, as well the complications due to the same procedure. An evaluation pre trabeculoplasty and a consecutive 5 visits will be perform as follows:

Visit 0 - Pre-procedure visit: the subjects that will undergo laser trabeculoplasty either Selective laser or PASCAL laser will be invited to participate and an informed consent will be carried out. The information concerting to demographics characteristics (study eye, age, gender and ethnicity), clinical characteristics (date of glaucoma diagnosis, number of medications used to treat glaucoma, time of use of actually anti-glaucomatous topical medication) and slit lamp and ophthalmoscopy examination (corneal aspect, iris color, pupil gonioscopy, intraocular pressure, lens status, vitreous cells, vertical C/D ratio, optic nerve edge, rim characteristic [ISNT pattern], peripapilar atrophy, state of fovea, state of peripheral retina and state of choroid for both eyes) will be extracted and recorded on respective case report form (CRF). The data will be scored according to the grading criteria outlined below:

Study eye: the eye under the follow-up 0 - Right eye 1 - Left eye

Geder: the state of being male or female 0 - Male 1 - Female

Ethnicity: the fact or state of belonging to a social group that has a common national or cultural tradition.

0 - Hispanic

1. - Black
2. - White
3. - Asian

Number of medications used: anti-glaucoma medication used by the patient 0 - 0

1. - 1
2. - 2
3. - 3
4. - 4

Corneal aspect: state in which the cornea is at baseline 0 - Normal 1 - Anormal

Iris color: iris pigmentation 0 - Light

1. - Medium
2. - Dark

Gonioscopy (Shaffer classification): amplitude of irido-corneal angle maseure by poster lens and noted by the Shaffer scale on each quadrant superior, nasal, temporal and inferor angle 0 - 0

1. - 1
2. - 2
3. - 3
4. - 4

Intraocular pressure: pressure inside the eye measured in millimeters of mercury Value in mmhg, measure with Goldman tonometer

Lens status: clouding of the lens Nuclear, Subcapsular and Cortical 0 - 0

1. - 1
2. - 2
3. - 3
4. - 4

Vitreous cells: number of cells per milimeter in the vitreous cavity 0 - 0 1 - traces 2 - +1 3 - +2 4 - +3 5 - +4

Vertical C/D ratio: relation between cup and optic nerve disc 0 - 0.1

1. - 0.2
2. - 0.3
3. - 0.4
4. - 0.5
5. - 0.6
6. - 0.7
7. - 0.8
8. - 0.9
9. - 1.0

Optic nerve edge: regularly over the optic disc 0 - Regular

1 - Irregular

Rim characteristic [ISNT pattern]: reduction pattern in the thickness of neural ring 0 - Conserved 1 - Not conserved

Peripapilar atrophy: presence of atrophy over the disc 0 - Alfa

1 - Beta 3 - Not apply

State of fovea: normality of the fovea 0 - normal

1 - abnormal

State of peripheral retina: state of the peripheral retina 0 - normal

1 - abnormal

State of choroid: choroidal health 0 - normal

1 - abnormal

After the visit 0, a 5 consecutive visits will be performed: for 1 day, 1 week, 1 month, 3 months and 6 months after the procedure. Identical data will be extracted, ophthalmological examination data, slit lamp exam, and the computerized visual fields (CVF) (CVF only at 3 and 6 months).

One member of the investigation team will collect all information during the follow-up time, and a second one member will review and collate data.

Statistical analysis will be performed in SPSS version 21. Univariate analyzes will perform; for categorical variables, frequency distribution will be made and reported in percentage, for the quantitative variables a measure of central tendency and dispersion will be made (mean, standard deviation and range) will calculate according to the relevance for each variable analyzed. Demographics such as age and gender variables will be described. For bivariate analysis comparing polytomous qualitative and quantitative variables (evolution of intraocular pressure with the type of trabeculoplasty used, number of antihypertensive medications required after the procedure with the type of trabeculoplasty, quantification of cellularity in the anterior chamber with type of trabeculoplasty) using parametric statistical analysis with ANOVA for independent samples and nonparametric with Kruskal-Wallis test. Also comparison of quantitative variables with quantitative variables (intraocular pressure before treatment and evolution of intraocular pressure after treatment) will be performed using the parametric inferential statistical Pearson correlation analysis and for nonparametric a Spearman correlation will be made. Finally, compare qualitative variables with qualitative variables (presence of peak intraocular pressure with type of laser trabeculoplasty performed) using the non-parametric statistical analysis Chi square test, Fisher exact test and Mac Nemar will make.