|Year : 2018 | Volume
| Issue : 1 | Page : 61-62
Department of Glaucoma, Al Salama Eye Hospital, Kannur, Kerala, India
|Date of Web Publication||7-Jun-2018|
Department of Glaucoma, Al Salama Eye Hospital, Kannur, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Cheriyath D. Journal Review. Kerala J Ophthalmol 2018;30:61-2
| Selective Laser Trabeculoplasty for Primary Open-Angle Glaucoma Patients Younger Than 40 Years|| |
Gupta V, Ghosh S, Sujeeth M, Chaudhary S, Gupta S, Chaurasia AK, Sihota R, Gupta A, Kapoor KS. Selective Laser Trabeculoplasty for Primary Open-Angle Glaucoma Patients Younger than 40 Years. Canadian Journal of Ophthalmology. 2018 Feb; 53(1):81-5.
Juvenile open-angle glaucoma (JOAG) is considered as primary glaucoma that lies between a spectrum ranging from primary congenital glaucoma to adult-onset open-angle glaucoma. The onset of glaucoma is before 40 years of age. JOAG is categorized separately from primary open-angle glaucoma (POAG) for a number of reasons. Age group of affected patients, elevated intraocular pressure (IOP) refractory to medical treatment, and functional disability due to visual loss are of special mention. These young patients belong to the working age group when diagnosed with glaucoma; hence, long-term topical glaucoma medication and the need to be compliant have a lot of impact on their quality of life. Selective laser trabeculoplasty (SLT) is a standard laser procedure offered to POAG patients, and its efficacy is well proven by a number of studies. SLT as a treatment option exclusively in JOAG patients has been less studied.
This study aims to evaluate the outcomes of SLT in JOAG patients and to assess the risk factors associated with treatment success or failure. The study passed the approval of ethics committee as per the Declaration of Helsinki. It was a prospective study done on consecutive JOAG patients on maximum tolerated medical treatment but uncontrolled IOP (above their target IOP).
All patients were of Indian origin, and one eye of each patient was included. If both eyes were eligible, the eye with higher prelaser IOP was selected for the study. SLT was performed using a Latina SLT lens (0.8–1 mJ, 90–110 spots, 360° angle). Postlaser, patients were continued on their previous antiglaucoma medication. The patients were followed up prospectively at day 1 and for 1, 3, 6, and 12 months postlaser. Success was defined as an IOP reduction of ≥20% at 12 months without further additional medication, laser, or surgery. Factors such as age and sex of the patient, number of prelaser medications, prelaser IOP, and gonioscopic features such as the presence of angle dysgenesis were evaluated.
The average prelaser IOP in these JOAG eyes (n = 30) was 25.3 ± 6.5 mmHg, which reduced to 17.3 ± 5.8 mmHg at 12 months (P = 0.01). Before laser, all patients were on topical glaucoma medications (range 2–5). Thirteen eyes (43%) had at least a 20% reduction of IOP with an average reduction of IOP of 37.6%. There was neither a difference in the prelaser IOP between those with success (25.5 ± 5.6 mmHg) and those that failed (25.1 ± 8 mmHg; P = 0.8) nor a difference in the mean age between eyes which achieved success (34.4 ± 9.4 years) and those that failed (31.6 ± 8.9 years; P = 0.4). There was no difference in the success rate between those <25 years of age and those >25 years of age. However, those without angle dysgenesis were 4.3 times (95% confidence interval 1.1–15.2) more likely to succeed with SLT than those with angle dysgenesis (P = 0.03).
This study found a 43% success rate of SLT when offered as a secondary treatment modality. Eyes with gonioscopically normal angle had a better success rate with SLT although there were exceptions to this observation. The success rate of SLT can be higher when offered as a primary treatment modality, unlike this study where SLT was done on eyes already on medication. Limitations of the study include the lack of a control group and a confounding effect due to regression to the mean. A randomized case–control study would have definitely added strength to the study and its results.
To conclude, a significant proportion of JOAG patients can benefit from an IOP reduction following SLT, especially those with normal-appearing open angle. If a noninvasive procedure such as SLT could wean patients off their medical treatment schedule, it would definitely bring a huge difference in the quality of life of these patients.
| Test Conditions in Macular Visual Field Testing in Glaucoma|| |
Eura M, Matsumoto C, Hashimoto S, Okuyama S, Takada S, Nomoto H, Tanabe F, Shimomura Y. Test Conditions in Macular Visual Field Testing in Glaucoma. Journal of Glaucoma. 2017 Dec; 26(12):1101-6.
Visual field (VF) charting is a vital investigation in glaucoma as it helps both clinician and patients to understand the impact of disease on the field of vision. Imaging has helped clinicians to detect glaucoma in the preperimetric stage itself as structural damage precedes functional loss. Newer versions of optical coherence tomography (OCT) can image and clearly segment all the retinal layers including the retinal ganglion cells (RGC). Maximum RGCs are in the macula, and hence, loss of any RGCs from this region of the retina is easy to detect. The corresponding VF test that could detect the functional loss due to the lost RGCs in the macula can serve best for the structure–function correlation, as it provides additional information regarding the pathology of glaucoma.
This study aims to find out the best macular VF test conditions such as target size, test type, and eccentricity for the macular region which can serve the purpose. Thirty-two eyes of 32 patients (61.1 ± 9.2 years) underwent an OCT to measure the ganglion cell layer (GCL) and inner plexiform layer (IPL) thickness and six VF tests. The eyes belonged to different stages of glaucoma such as preperimetric (6), early-stage (16), and moderate-stage (10) stages. GCL + IPL thickness was measured by spectral-domain OCT (SD-OCT) with a macular 7 mm × 7 mm cube scan (3D OCT-2000, Topcon). The six VF tests included three standard automated perimetry (SAP) (10-2 HFA using SITA with target size III [HFA SITA (III)], full threshold with size III [HFA FULL (III)], and full threshold with size I [HFA FULL (I)]) and three visual function-specific perimetry tests (10-2 SWAP, 10-2 flicker, and 10-2 Humphrey Matrix). The coefficient of determination (r2) for the correlation between visual sensitivity and the GCL + IPL thickness was calculated using linear and quadratic regressions for each test at eccentricities 0°–5°, 5°–7°, and 7°–10°, as RGC density varies with eccentricity.
The study results showed that at the macula, SAP with target size I and the 3-visual function-specific perimetry tests (particularly, the SWAP and Matrix) had a stronger linear relationship with the GCL + IPL thickness than the normal SAP with target size III. This was due to the overlap in the stimulation of adjacent RGCs and their receptive fields caused by size III stimulus than a size I stimulus. Visual function-specific perimetry tests are more sensitive than SAP in detecting early glaucomatous field defects as they target-specific K or M subtypes of RGCs, which have thicker axons and so get first damaged in early glaucoma. Matrix showed the strongest correlation with GCL + IPL thickness among the three visual function-specific tests, though studies showed that FDT stimulated the P-cells more than M-cells. The reasons for this strong correlation are the unique nature of test points in matrix and the ZEST algorithm used in matrix instead of the standard bracketing strategy. Regarding the eccentricity, this study found the best structure–function correlation between 5° and 7°. The reason for this being, within the central 5°, the high density of RGCs precluded detection of early field defects due to overlap of their receptive fields, and beyond 7°, there was a drastic decline in RGC density, which caused a very small structural damage if at all any.
To conclude, the macular VF abnormalities detected by various tests in this study corresponded well with the locations showing abnormal GCL + IPL thickness particularly at eccentricity 5°–7°. In early glaucoma when the GCL + IPL thickness only changes slightly, SAP with a smaller target of size I and visual function-specific perimetry, especially Matrix, can better detect early glaucomatous abnormalities than the commonly used SAP with target size III.
- Dr. Shabana Bharathi, Ex Glaucoma Fellow, Aravind Eye Hospital, Coimbatore.
- Dr. Mrunali Dhavaliker, Medical Officer, Department of Glaucoma, Aravind Eye Hospital, Coimbatore.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.