[Recommendations for follow-up examinations in patients with ocular hypertension]

[Are diurnal and nocturnal intraocular pressure measurements over 48 h justified?]

PURPOSE

Diurnal intraocular pressure (IOP) measurements are recommended in cases of visual field deterioration in glaucoma patients. In this study the rationale of 24 h versus 48 h IOP measurements was investigated.

PATIENTS AND METHODS

Mean IOP and maximum IOP values were obtained in 80 patients over a period of 48 h. The IOP measurements (Goldmann tonometry) of day 1 and 2 (taken every 4 h) were compared. To reduce interindividual and intraindividual differences of measurements the statistical calculation took a tolerance level of ± 2 mmHg and ± 1 mmHg into account.

RESULTS

Maximum IOP measurements were found to differ between 37.5 % and 65.0% respectively for right eyes and 28.8 % and 47.5% respectively for left eyes depending on the measurement tolerance (±2 mmHg or ±1 mmHg) between day 1 and day 2. Mean IOP values were found to differ by 25 % and 51.3 % respectively for right eyes and 26.3 % and 46.3% respectively for left eyes (± 2 or ± 1 mmHg in) between day 1 and day 2. A time-related clustering of extreme deviations could not be found but the maximum values from all patients were found to be roughly equally distributed over daytime and nighttime hours.

CONCLUSIONS

Both maximum IOP and mean IOP measurements were found to differ by at least ± 2 or ± 1 mmHg between day 1 and 2 at a significant percentage and the maximum values did not peak at a predictable time point during the 48 h. Therefore, 48 h IOP measurements appear to be more reliable than 24 h measurements.

[Fundus perimetry in functional diagnostics of glaucoma. Applicable in the practice?]

Examination of the visual field using static automated perimetry (SAP) is the method of choice for the detection of functional damage secondary to glaucoma. However, with SAP early visual field defects might be missed even if there is already visible damage of the retinal nerve fibre. The microperimetry or beter fundus perimetry provides a detailed examination of the differential luminance threshold within defined retinal areas. However, in contrast to lesions of the retinal receptors, in cases of glaucomatous damage the retinal fibre course has to be considered resulting in a displacement between the structural lesion and the location of the related functional defect. The functional damage may be detected at earlier stages and with enhanced spatial resolution compared to conventional SAP. The extra costs and time associated with the application of fundus perimetry have prevented its widespread use. Current developments are leading to new options.