Laminar displacement and prelaminar tissue thickness change after glaucoma surgery imaged with optical coherence tomography.
OBJECTIVE
To study changes in lamina cribrosa position and prelaminar tissue thickness (PTT) after surgical IOP reduction in glaucoma patients.


METHODS
Twenty-two patients (mean age, 71.4 years) were imaged with spectral domain optical coherence tomography (SD-OCT; 24 radial B-scans centered on the optic nerve head [ONH]) before trabeculectomy or tube shunt implantation. Follow up images were acquired 1 week, 1 month, 3 months, and 6 months postsurgery. Bruch's membrane opening (BMO), the internal limiting membrane (ILM) and the anterior laminar surface (ALS) were segmented in each radial scan with custom software. Surfaces were fitted to the ILM and ALS with the extracted three-dimesional coordinates. PTT was the distance between the ILM and ALS, perpendicular to a BMO reference plane. Serial postsurgical laminar displacement (LD), relative to the BMO reference plane, and changes in PTT were measured. Positive values indicated anterior LD.


RESULTS
Mean (SD) presurgery IOP was 18.1 (6.5) mm Hg, and reduced by 4.7 (5.5), 2.4 (7.7), 7.0 (6.2), and 6.8 (7.5) mm Hg at 1 week, 1 month, 3 months, and 6 months postsurgery, respectively. At the four postsurgery time points, there was significant anterior LD (1.8 [9.5], -1.1 [8.9], 8.8 [20.2], and 17.9 [25.8] μm) and PTT increase (1.7 [13.3], 2.4 [11.9], 17.4 [13.7], and 13.9 [18.6] μm). LD was greater in ONHs with larger BMO area (P = 0.01) and deeper ALS (P = 0.04); however, PTT was not associated with any of the tested independent variables.


CONCLUSIONS
Both anterior LD and thickening of prelaminar tissue occur after surgical IOP reduction in patients with glaucoma.
Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
Alexandre S C
AS
Reis
Neil
N
O'Leary
Miriam J
MJ
Stanfield
Lesya M
LM
Shuba
Marcelo T
MT
Nicolela
Balwantray C
BC
Chauhan
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D020327:Glaucoma Drainage Implants; D005902:Glaucoma, Open-Angle / Q000503:physiopathology / Q000601:surgery*; D006068:Gonioscopy; D006801:Humans; D021621:Imaging, Three-Dimensional; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D011446:Prospective Studies; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D014130:Trabeculectomy; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology