Anterior Chamber Angle Examination in Angle Closure Suspect Patients

Glaucoma is a form of progressive optic neuropathy and is one of the leading causes of preventable blindness worldwide. The average life span is increasing leading to more individuals developing glaucoma as well as having the disease longer, which makes early detection and management very important.[1] Glaucoma is characterized by loss of retinal ganglion cells (RGCs) recognized as optic nerve head (ONH) changes, corresponding visual field (VF) defects and retinal nerve fiber layer (RNFL) loss. At least 40% of RGCs are lost before the VFs show a defect, hence the emphasis on early diagnosis in the stage of glaucoma suspect.[2] There are two types of glaucoma suspect: Primary Open angle and primary angle closure suspect.(3) Primary angle-closure (PAC) suspects can be detected by the following: the trabecular meshwork can only be seen in 180º or less of anterior chamber angle (AC) by gonioscopy, the intraocular pressure(IOP) remains within normal limits and no structural damage to the optic nerve is present.[4] Time domain Optical coherence tomography (TD-OCT) was initially designed to image the posterior segment and retina, but its capability to generate cross-sectional images of internal biological structures without contacting the ocular surface was quickly adapted to visualize the anterior segment and cornea.[5].

Spectral domain anterior segment OCT (SD-OCT) technology allow visualizing the anterior chamber angle of the eye with high speed and high resolution. Spectral-domain OCT(SD OCT) instruments working at 840 nm can reliably identify fine angle structures such as Schwalbe's line.(6) Scheimpflug imaging also offers non-contact imaging of the anterior segment. Although Scheimpflug photography cannot fully visualize the entire angle, the software available on the Pentacam system (Oculus Optikgeräte, Wetzlar, Germany) provides extrapolated measurements of the anterior chamber volume (ACV), which have shown promise in screening for narrow angles.(7)

Inclusion criteria

• Hyperopes. 2-Shallow AC. 3-With gonioscopy carried out under dim-light conditions without indentation ,with the eye in primary position there is inability to visualize ≤ 180° of the posterior trabecular meshwork (TM) in the absence of peripheral anterior 4-IOP ≤ 21 as measured by tonometry. 5-Normal visual field on static automated perimetry (SAP) testing. 5-Normal optic nerve head (ONH) appearance on fundus biomicroscopy. 6-Family history of primary angle closure disease.

Exclusion criteria

• 1-Eyes with significant corneal opacity that can impare signal strings of any of the used imaging modalities.

2-Eyes wih history of intraocular surgery (e.g. cataract surgery ,retinal detachment surgery).

3-Eyes with history of laser procedures (e.g.laser peripheral iridotomy). 4-Eyes with anterior segment pathology as iridocyclitis or angle disgenesis 5. Eyes with history of trauma. 6- Eyes with findings suggestive of 2dry cause of glaucoma (e.g. iris or angle neovascularization, any iris or corneal abnormalities, dilated episcleral vessels ).