Abstract
Purpose:
To develop methodology for automated measurement of retinal vessel diameters on scanning laser ophthalmoscopy(SLO) images and to apply this, in a pilot manner, to images from patients with papilledema and pseudopapilledema.
Methods:
SLO images of optic discs(Spectralis, Heidelberg Engineering) were acquired in subjects with papilledema(n=3, age 23-50 yrs, lumbar puncture(LP) opening pressure(OP) 34-37cm) prior to LP and subjects with pseudopapilledema(n=3, 14-70 years, LP OP 14.5-24cm). Follow-up images were obtained 5 months after treatment for intracranial pressure in 3 papilledema subjects and 18 months after the first scan in 1 pseudopapilledema subject. An automated customized image analysis software was developed using Matlab(Mathworks) to measure the diameters of superior and inferior retinal arteries and veins 3mm from the optic nerve head center. These automated measurements were compared against manual measurements obtained using a commercial software package(Eye Explorer, Heidelberg Engineering). Automated vessel measurements were compared between subjects with papilledema and pseudopapilledema.
Results:
Automated measurements of vessel diameters were successfully obtained for 85% of arteries(n=40) and 95% of veins(n=40). Automated measurements were, on average, within 7% and 10% of manual measurements of arteries and veins, respectively. Compared with pseudopapilledema subjects, all 3 papilledema subjects prior to LP had larger superior vein diameters(p=0.05 Mann-Whitney(MW)) and 2 out of 3 had larger inferior vein diameters(p=0.28 MW). Arterial diameters were similar between the two groups. Longitudinal analysis of 12 veins in papilledema subjects showed vein diameter 5 months after treatment to decrease in 8, be stable in 1, increase in 1 and not be measurable in 2. The magnitude of vein diameter change in a pseudopapilledema subject was less than that in 70% of veins in papilledema subjects.
Conclusions:
Retinal artery and vein diameters automatically quantified from SLO images demonstrated increased vein diameter in papilledema subjects prior to LP and reduced vein diameter following treatment for intracranial pressure. This finding agrees with reports of decreased retinal vein caliber following optic nerve sheath decompression in papilledema(Lee et al, Ophth Surg 1995;26:25). Further study is needed to determine the clinical utility of retinal vein diameter measurements as a marker for diagnosis and treatment of papilledema.
Keywords: 629 optic nerve •
550 imaging/image analysis: clinical •
436 blood supply