Evaluation of the optic nerve and scleral-choroidal-retinal layer with ultrasound elastography in glaucoma and physiological optic nerve head cupping.

AIM: To evaluate the strain ratio of the optic nerve and retina-choroid-sclera (RCS) layers in individuals with physiological optic disc cupping (PC) and glaucoma patients using strain elastography. MATERIAL AND METHODS: We evaluated 56 eyes of 56 subjects (20 eyes with glaucoma, 19 eyes with PC, and 17 normal eyes). The strain ratio of orbital fat to optic nerve (SROFON) was calculated as the ratio of the optic nerve to intraconal fat tissue and the strain ratio of orbital fat to retina-choroid-sclera (SROFRCS) was calculated as the ratio of RCS layers to intraconal fat tissue. RESULTS: SROFON was 0.92 in the control group, 1.07 in the PC group and 1.6 in the glaucoma group and a statistically significant difference was present between the three groups (p<0.05). SROFRCS had no statistically significant difference between the three groups. CONCLUSIONS:  SROFON values could contribute to the differentiation of the patients with glaucoma and PC.

Chorioretinal temperature monitoring during transpupillary thermotherapy for choroidal neovascularisation.

AIMS: To investigate the difference in temperature rise between normal choroid and choroidal revascularisation (CNV) during transpupillary thermotherapy (TTT) and the relation between laser spot size and power in the rat fundus. METHODS: A modified slit lamp, which was installed with two laser wavelengths (490 nm for illumination and fluorescein excitation and 810 nm for hyperthermia), was developed for TTT and temperature monitoring. Temperature rise during TTT was monitored by observing fluorescence released from thermosensitive liposomes encapsulating carboxyfluorescein. Two types of liposomes were prepared; their phase transition temperatures were 40 degrees C and 46 degrees C, respectively. Laser power settings required to observe fluorescence released from 46 degrees C liposome in normal choroid or CNV were compared. Next, the power settings with 0.5 mm and 0.25 mm spot sizes were compared following administration of 40 degrees C liposome or 46 degrees C liposome. RESULTS: The minimum power values when release from 46 degrees C liposome was observed showed a significant difference in distribution of power values between normal choroid and CNV. CNV required significantly higher power than normal choroid. With 40 degrees C liposome, the power was 9.7 (1.9) mW (mean (SD)) at a spot size of 0.25 mm, and 12.1 (1.6) mW at 0.5 mm, respectively. When using 46 degrees C liposome, the power setting was 10.2 (1.2) mW at a spot size of 0.25 mm, and 14.6 (2.2) mW at 0.5 mm, respectively. CONCLUSIONS: CNV demonstrated varying heat conduction, compared with normal choroid. Laser power required to raise the temperature should not necessarily be doubled, even when the spot size is doubled. Close attention should be given to the selection of power settings when performing TTT for CNV.