Topouzis_edit_Cardiology_book_temp 21/01/2010 12:19 Page 30
Glaucoma
Structural Changes Observed with Clinical Progression of Glaucoma
Fotis Topouzis and Panayiota Founti
Department of Ophthalmology, School of Medicine, Aristotle University of Thessaloniki, AHEPA Hospital, Thessaloniki
Abstract
Glaucoma progression can be assessed based on the worsening of functional and/or structural damage. The importance of assessing structural
changes relies on the fact that these usually precede visual field defects in the course of glaucoma. Changes in specific optic disc features
denoting glaucoma progression can be clinically observed, while the occurrence of disc haemorrhages is considered to be a risk factor for
glaucoma progression. To date, colour photography of the optic disc is the standard method for documenting and monitoring glaucoma in clinical
practice and research studies. However, there are several limitations related to the use of colour photography. These mainly involve moderate to
poor reproducibility in assessing glaucoma progression and limited information provided on the amount of glaucomatous damage progression.
Keywords
Glaucoma, progression, optic disc, rim, retinal nerve fibre layer, cup-to-disc ratio, colour photography
Disclosure: The authors have no conflicts of interest to declare.
Received: 3 August 2009 Accepted: 2 October 2009
Correspondence: Fotis Topouzis, Aristotle University of Thessaloniki, School of Medicine, Department of Ophthalmology, General Hospital ‘AHEPA’, S Kiriakidi 1,
54636, Thessaloniki, Greece. E:
ftopouzis@otenet.gr
Support: Supported by Pfizer. The views expressed are those of the authors and not necessarily those of Pfizer.
Assessing Glaucoma Progression grading by two masked graders.
4
As opposed to the aforementioned
Criteria used to define glaucoma progression usually rely on the studies, the Collaborative Initial Glaucoma Treatment Study (CIGTS)
5
worsening of functional and/or structural damage.
1
However, as yet and the Advanced Glaucoma Intervention Study (AGIS)
6
used only
there are no universally accepted criteria for glaucoma progression. functional damage criteria to define glaucoma progression.
Suitable criteria to define progression may differ depending on the
purpose of the study. As has been suggested in an editorial by The diversity of criteria for glaucoma progression used in the above
Anderson et al., evaluating the course of a disease in an individual RCTs could be related to the fact that the OHTS and the EMGT
patient may be different from identifying small differences in the enrolled subjects with ocular hypertension and earlier stages of
average course between two or more study groups. It is also different glaucoma, respectively, whereas CIGTS and the AGIS included
from ascertaining the safety of each individual enrolled in a clinical subjects with advanced glaucoma damage. Also, the CIGTS criteria for
trial.
2
Furthermore, with regard to clinical studies, the progression of glaucoma progression were based on visual field only. However, in a
one parameter may be more appropriate than others because studies recent report by the same study group, baseline and follow-up
may vary in purpose.
2
photographs were assessed by two masked graders to determine the
five-year incidence of glaucomatous optic disc progression.
7
In this
Criteria for Glaucoma Progression in report, optic disc change was recorded as a dichotomous state: no
Randomised Clinical Trials change in cup-to-disc ratio in any meridian versus enlargement of
Previous randomised clinical trials (RCTs) have used different criteria cup-to-disc ratio in any meridian.
to define glaucoma progression. In the Ocular Hypertension
Treatment Study (OHTS)
3
and the Early Manifest Glaucoma Trial Structural and Functional Damage in the
(EMGT),
4
glaucoma progression was defined based on the worsening Course of Glaucoma
of both structural and functional damage. With regard to structural Histological studies suggest that a substantial number of retinal ganglion
damage, in the OHTS progression was defined by generalised or cells are lost before the development of visual field damage.
8,9
It has also
localised thinning of the neuroretinal rim compared with baseline. This been shown that in the earlier stages of glaucoma, optic disc changes
was determined based on baseline and follow-up stereophotographs are more prominent than visual field defects; however, in the later
assessed by two masked graders.
3
In the EMGT, the worsening of stages of the disease visual field changes are more prominent
structural damage was defined as the progression of optic disc compared with morphological changes.
10
The fact that structural
cupping. This was determined based on baseline and follow-up changes may precede functional changes during the course of
photographs assessed with flicker chronoscopy and side-by-side glaucoma is further supported by the OHTS, where primary open-angle
30 © TOUCH BRIEFINGS 2009
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