Multiple imaging modalities for the detection of optic nerve head drusen: Is echography still mandatory?

Reply to Schimmelbusch, K.J.; Collison, F.T. Comment on "Rosa et al. Optic Nerve Drusen Evaluation: A Comparison between Ultrasound and OCT. J. Clin. Med. 2022, 11, 3715"

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Optic nerve sheath diameter and axial length in patients with optic disc drusen: a cross-sectional study

AIM

Measuring the optic nerve sheath diameter (ONSD) and the anteroposterior axial length of the eye in patients with optic disc drusen (ODD).

METHODS

A total of 43 healthy volunteers and 41 patients with ODD were included in the study. The ONSD and axial length were measured in the posterior position using an ultrasound device (E-Z Scan AB5500 +) probe with a 10 MHz frequency. The ONSD was measured 3 mm behind the globe wall. Receiver operating characteristic (ROC) curve analysis was performed to determine patients with ODD using ONSD. Any p-value of < 0.05 was accepted to demonstrate significance.

RESULTS

The ONSD was significantly higher (5.2 mm and 4.8 mm, p = 0.006, respectively), and the axial length was shorter (21.82 ± 2.15 mm and 23.27 ± 1.96 mm, p = 0.002, respectively) in the ODD group. The spherical equivalent was more commonly seen as hypermetropic in the ODD group (1.00 [- 0.85 to 1.75]). In the ROC analysis to determine the ONSD value in ODD diagnosis, the area under the curve was 0.6754 (95% confidence interval 0.559-0.788, p = 0.006). ONSD cutoff of 5.70 mm had a sensitivity of 0.366 and a specificity of 0.907 to diagnose ODD.

CONCLUSION

In this study, the ONSD was significantly higher in the ODD group. The axial length was shorter in the ODD group. This study is the first in the literature to evaluate the ONSD in patients with optic disc drusen. Further studies are needed in this regard.

Optic Nerve Drusen Evaluation: A Comparison between Ultrasound and OCT

This observational study compared optic coherence tomography (OCT) and B-scan in the detection of optic disc drusen. In total, 86 eyes of 50 patients with optic disc drusen (ODD) (36 bilateral) with a mean age of 34.68 ± 23.81 years, and 54 eyes of 27 patients with papilledema, with a mean age of 35.42 years ± 17.47, were examined. Patients with ODD, diagnosed with ultrasound, underwent spectral-domain OCT evaluation. With US, 28 ODD cases were classified as large (4 buried and 24 superficial), 58 were classified as point-like (6 buried, 49 superficial and 3 mixed). Then, all patients underwent OCT. OCT was able to detect the presence of ODD and/or peripapillary hyperreflective ovoid mass structure (PHOMS) in 69 eyes (p < 0.001). In particular, 7 eyes (8.14%) showed the presence of ODD alone, 25 eyes (29.07%) showed only PHOMS and 37 eyes (43.02%) showed ODD and PHOMS. In 17 eyes (19.77%) no ODD or PHOMS were detected. In the papilledema group, no ODD were observed with both US and OCT. OCT showed the presence of drusen or similar lesions in only 80.23% of the cases highlighted by the US scan, so it does not allow for certain ODD diagnoses, especially in the case of buried ODD.

Optic Nerve Head Drusen: An Update

Optic nerve head drusen are benign acellular calcium concretions that usually form early in life, just anterior to the lamina cribrosa. Improving imaging using optical coherence tomography suggests they are common and may be present in many clinically normal discs. These drusen may change in appearance in early life, but are generally stable in adulthood, and may be associated with visual field defects, anterior ischaemic optic neuropathy, or rarer complications. Based on long-term clinical data and optical coherence tomography, we propose a refined hypothesis as to the cause of optic disc drusen. Here we summarise recent findings and suggest future studies to better understand the forces involved.

Variability of choroidal and retinal thicknesses in healthy eyes using swept-source optical coherence tomography - implications for designing clinical trials

Aim

The aim was to study the variability of choroidal scleral interface (CSI) thickness in healthy subjects and its relevance for designing future studies.

Methods

A total of 123 volunteers were imaged using swept-source optical coherence tomography. Early treatment diabetic retinopathy grid was used.

Results

Mean central retinal thickness was 285.85±14.53 µm and 287.18±12.93 µm, and mean central CSI thickness was 273.94±77.77 µm and 271.19±78.85 µm for the right and left eyes, respectively. Mean retinal and CSI thicknesses correlated negatively with age (p=0.023, r=−0.208 and p<0.0001, r=−0.426, respectively) and axial length (p=0.016, r=−0.220 and p<0.0001, r=−0.504, respectively). To detect a CSI change of at least 112 µm, a sample size of 11 or 36 per group is needed for a single- or double-arm study, respectively (α=0.05, power =0.90, no loss to follow-up, assuming standard deviation in future studies as 100 µm).

Conclusion

Future clinical studies using CSI as end point are possible with regard to sample size needed.