Retrobulbar blood flow in patients with cataract

Evidence of vascular involvement in myopia: a review

The benign public perception of myopia (nearsightedness) as a visual inconvenience masks the severity of its sight-threatening consequences. Myopia is a significant risk factor for posterior pole conditions such as maculopathy, choroidal neovascularization and glaucoma, all of which have a vascular component. These associations strongly suggest that myopic eyes might experience vascular alterations prior to the development of complications. Myopic eyes are out of focus because they are larger in size, which in turn affects their overall structure and function, including those of the vascular beds. By reviewing the vascular changes that characterize myopia, this review aims to provide an understanding of the gross, cellular and molecular alterations identified at the structural and functional levels with the goal to provide an understanding of the latest evidence in the field of experimental and clinical myopia vascular research. From the evidence presented, we hypothesize that the interaction between excessive myopic eye growth and vascular alterations are tipping-points for the development of sight-threatening changes.

The discovery of the Flammer syndrome: a historical and personal perspective

This review describes the clinical and basic research that led to the description of Flammer syndrome. It is narrated from a personal perspective. This research was initiated by the observation of an increased long-term fluctuation of visual fields in a subgroup of glaucoma patients. As these patients had strikingly cold hands, peripheral blood flow was tested with a capillary microscopy, and vasospastic syndrome (VS) was diagnosed. Further studies on these patients revealed frequently weakened autoregulation of ocular blood flow and increased flow resistivity in retroocular vessels. Their retinal vessels were more rigid and irregular and responded less to flickering light. Holistic investigation demonstrated low blood pressure, silent myocardial ischaemia, altered beat-to-beat variation, altered gene expression in the lymphocytes, slightly increased plasma endothelin level and increased systemic oxidative stress. This combination of signs and symptoms was better described by the term primary vascular dysregulation (PVD) than by VS. Subsequent studies showed additional symptoms frequently related to PVD, such as low body mass index, cold extremities combined with slightly increased core temperature, prolonged sleep onset time, reduced feelings of thirst, increased sensitivity to smell and also for certain drugs and increased retinal venous pressure. To better characterise this entire syndrome, the term Flammer syndrome (FS) was introduced. Most subjects with FS were healthy. Nevertheless, FS seemed to increase the risk for certain eye diseases, particularly in younger patients. This included normal-tension glaucoma, anterior ischaemic optic neuropathy, retinal vein occlusions, Susac syndrome and central serous chorioretinopathy. Hereditary diseases, such as Leber’s optic neuropathy or retinitis pigmentosa, were also associated with FS, and FS symptoms and sings occurred more frequent in patients with multiple sclerosis or with acute hearing loss. Further research should lead to a more concise definition of FS, a precise diagnosis and tools for recognizing people at risk for associated diseases. This may ultimately lead to more efficient and more personalised treatment.

Evaluation of retrobulbar blood flow in patients with age-related cataract; color Doppler ultrasonographic findings

Objectives

Cataracts are the most common cause of blindness worldwide, with cataract surgery being the most common ophthalmic procedure. To our best knowledge, this is the first case-control study with a large number of participants to evaluate ocular blood flow in patients with cataracts.

Materials and methods

Color Doppler and duplex sonography of the orbital vessels was performed in 224 eyes of 112 patients with known bilateral age-related cataracts and in 76 eyes of 38 healthy age- and sex-matched volunteers.

Results

The mean ± (standard deviation [SD]) of peak systolic velocity (PSV) of the ophthalmic artery in patients with cataracts (34.59 ± 22.49 cm/second) was significantly different to that in controls (52.11 ± 14.01 cm/second) (P < 0.001). The mean ± SD PSV of the central retinal artery in patients with cataracts (15.31 ± 4.93 cm/second) was significantly different to that in controls (9.61 ± 5.64 cm/second) (P < 0.001).

Conclusion

The mean PSV and resistive index (RI) of the ophthalmic and central retinal arteries were lower in cataract patients when compared with normal subjects. This suggests that ocular hypoperfusion and changes in ocular hemodynamic may have a role in the formation of age-related cataracts.

Comparision of the effects of subtenon’s and subconjunctival anesthesia on retroorbital hemodynamics

The aim of the study was to compare retroorbital blood flow hemodynamics between subconjunctival and sub-Tenon’s anesthesia. This was a prospective, blinded study and included 80 cases. Patients were monitored and treated in the First Ophthalmology Clinic, Ataturk Training and Research Hospital, Turkey. Sub-Tenon’s anesthesia was performed in 42 cases, and subconjunctival anesthesia was performed in 38 cases. Color Doppler imaging to measure ocular blood flow parameters was performed preoperatively and 21 days after cataract operation in each case. Preoperative and postoperative values of resistivity and pulsatility indices in the ophthalmic, central retinal, and short posterior ciliary arteries were compared. Postoperative mean blood flow velocity measurements of ophthalmic artery were not statistically different between the subconjunctival anesthesia group and the sub-Tenon’s anesthesia group (49.63 ± 14.00 vs. 45.85 ± 13.41; P=0.389). Postoperative RI values were higher in the Subtenon’s anesthesia group than in the subconjunctival anesthesia group, but the difference between two groups was not statistically significant (0.81 ± 0.14 vs. 0.74 ± 0.08; P=0.079). The postoperative pulsatility index of the ophthalmic artery, RI of ophthalmic artery, pulsatility index of the central retinal artery, RI of the central retinal artery, and pulsatility index of the posterior ciliary arteries were not significantly different between the subconjunctival and sub-Tenon’s anesthesia groups. In conclusion, the study suggests that postoperative retroorbital blood flow hemodynamics are the same following sub-Tenon’s and subconjunctival anesthesia.