Open Angle Glaucoma – Diagnosis, Follow-up, and Treatment

SBU’s Conclusions

This section summarizes the findings from SBU’s assessment of diagnosis, follow-up, and treatment of chronic, open angle glaucoma and elevated intraocular pressure (ocular hypertension, OH). Glaucoma is a disease affecting the optic nerve, leading to visual field defects. The causes of glaucoma are not fully understood, but elevated intraocular pressure is the most important risk factor. Diagnosis involves examining the visual field, optic disc, and retinal nerve fiber layer. Although intraocular pressure is also measured, it is not part of the diagnostic definition of glaucoma. All treatment strategies aim at reducing intraocular pressure to delay progression of the disease.

Diagnosis

Visual field testing (perimetry)

• New testing methods (SITA tests for the Humphrey perimetry) yield high diagnostic accuracy for glaucoma and take approxi-mately half the time of previous tests (Limited scientific evidence: Evidence Grade 3).

Examination of the optic nerve and retina

• In assessment of the optic disc, mono- or stereophotographs yield low to moderately high diagnostic accuracy (Limited scientific evidence: Evidence Grade 3).
• In examination of the optic disc, scanning laser tomography (Heidelberg tomography) is equal or superior to expert judge-ment as regards the ability to distinguish normal discs from those affected by glaucoma (Limited scientific evidence: Evidence Grade 3).
• In examination of the retinal nerve fiber layer, scanning laser polarimetry (the newer GDx instruments) and optical coherence tomography (Stratus OCT) yield moderately high and approximately equal diagnostic accuracy (Limited scientific evidence: Evidence Grade 3).

Treatment

• In manifest glaucoma, treatment to reduce intraocular pressure delays the progression of visual field loss (Limited scientific evidence: Evidence Grade 3).
• In individuals with elevated intraocular pressure (ocular hyper-tension), treatment that lowers the intraocular pressure by 20%, or more, reduces the risk for developing manifest glaucoma in the treated eye (Limited scientific evidence: Evidence Grade 3). This effect has not been demonstrated when the reduction in intraocular pressure is less than 20%.
• No conclusive evidence shows whether surgical or laser treatment strategies are more effective than medical treatment (topical eye drops) in lowering intraocular pressure (Contra-dictory scientific evidence).

Ethical and Social Aspects

• Due to the slow course of glaucoma and the relatively high age of patients, there is a risk that examination and treatment are given low priority. Hence, special attention should be directed at assuring that the needs for diagnosis, follow-up, and treatment are met among these patients.

Health Economics

• No conclusive evidence shows which methods of diagnosis, follow-up, and treatment for glaucoma are the most cost  effective (Insufficient scientific evidence).