Guided Trocar Insertion in Highly Myopic Eyes

PURPOSE

To demonstrate through a diagnostic test used as a new preoperative assessment that trocar insertion for pars plana vitrectomy could be safely placed at a distance >4.0 mm in highly myopic eyes to facilitate the surgical maneuvers.

METHODS

Thirty eyes of 30 patients were tested with a biometer for the axial length measurement and with ultrasound biomicroscopy to measure the pars plana length. Pars plana lengths of highly myopic eyes were then compared with those of emmetropic eyes. The surgeon also measured the pars plana of highly myopic eyes intraoperatively and compared it with ultrasound measurements to assess ultrasound biomicroscopy reliability.

RESULTS

The mean axial length was 23.81 mm (SD ± 0.30) in the control group and 31.11 mm (SD ± 0.56) in the myopic group. The mean pars plana length was 4.96 mm (SD ± 0.19) in control eyes and 6.65 (SD ± 0.36) in myopic eyes. An extremely significant statistical difference ( P < 0.001) was obtained by comparing the length of pars plana between control eyes and myopic eyes. The results of pars plana measurements were 6.65 mm (SD ± 0.36, ultrasound biomicroscopy) and 6.66 mm (SD ± 0.34, intraoperative measurements) in myopic eyes. The statistical comparison of the measurements in these two groups did not give a statistically significant result ( P = 0.950).

CONCLUSION

Ultrasound biomicroscopy is a reliable technique to calculate the length of pars plana in highly myopic eyes, where this parameter is significantly greater than that of emmetropic eyes. Trocars insertion for pars plana vitrectomy may be performed, in eyes with axial length >30 mm, in relative safety at a distance to limbus higher than 4 mm.

Peripapillary choroidal thickness in eyes with high myopia

Objective

To investigate characteristics of peripapillary choroidal thickness (PCT) in Chinese patients with myopia without myopic maculopathy.

Methods

We retrospectively assessed 95 Chinese patients (95 eyes) with myopia without myopic maculopathy, who had visited the myopia clinic of Shandong Provincial Qianfoshan Hospital. Thirteen patients were excluded; the remaining 82 patients were divided into Groups 1 (spherical equivalent [SE], −0.5 to −6.0 D; axial length, 24–26 mm; n = 26), 2 (SE, −6.0 to −10.0 D; axial length, 26 to 28 mm; n = 34), and 3 (SE, ≥−10.0 D; axial length, ≥28 mm; n = 22). Enhanced depth imaging optical coherence tomography was used to measure PCT in inferior, superior, nasal, and temporal quadrants. Continuous variables were compared using one-way analysis of variance. Associations of PCT with SE and axial length were analyzed by Pearson correlation.

Results

PCT decreased with increasing SE and axial length in all quadrants. For each group, PCT was thickest in the temporal quadrant and thinnest in the inferior quadrant. PCT significantly differed between Groups 1 and 3 in superior, nasal, and temporal quadrants.

Conclusions

PCT decreased with increasing SE and axial length. PCT was thickest in the temporal quadrant and thinnest in the inferior quadrant in Chinese patients with myopia.

Corneal endothelial cell density and morphology in low and moderate myopic Chinese eyes

AIM

To describe and compare the corneal endothelial cell density and morphology in young, low and moderate myopic Chinese adults in Malaysian Chinese population.

METHODS

Non-contact specular microscopy (Topcon SP3000P, Tokyo, Japan) was performed in low (n=78; 21.22±1.51 years) and moderate (n=78; 21.82±1.40 years) myopic subjects. The mean of three consecutive measurements of endothelial cell density (MCD), coefficient of variation (CV) in the cell size, and hexagonal appearance of the cell were obtained.

RESULTS

In low myopic eyes the MCD was 3 063.0±176.2/mm(2), the mean CV was 33.4±4.0% and the mean hexagonal appearance of the cell was 57.9±2.7%. In moderate myopic eyes the MCD was 2961.6±159.0/mm(2), the mean CV was 33.9±3.6% and mean hexagonal appearance of the cell was 56.2±4.7%. There were statistically significant differences in MCD (P<0.000) and hexagonal appearance of the cell (P<0.005) between low and moderate myopic eyes.

CONCLUSION

The corneal endothelial cell layer in more myopic eyes tends to have less MCD and cell hexagonality compared to lower myopic eyes. Nevertheless, there is no significant difference in CV between low and moderate myopic eyes.

Peripapillary crescent enlargement in highly myopic eyes evaluated by fluorescein and indocyanine green angiography

AIMS

To evaluate angiographic features of myopic crescents using fluorescein angiography (FA) and indocyanine green angiography (IA).

METHODS

FA and IA angiograms of 88 highly myopic eyes (47 consecutive patients) were reviewed. The follow up period ranged from 5-28 years.

RESULTS

FA revealed two zones of the myopic crescent: a consistently hypofluorescent inner zone and an outer zone with delayed choroidal filling. IA revealed dislocation of the Zinn-Haller ring to the border between the two zones. Myopic crescent enlargement occurred in 68.1%. Only the outer zone increased significantly in most of the eyes with enlarged crescents.

CONCLUSIONS

The inner zone might develop as a result of mechanical stretching, and the outer zone might be the result a secondary circulatory disturbance and mechanical stretching.