Retinal Vessels and High Myopia

Abstract

High myopia is a cause of legal blindness worldwide, and the visual impairments are due to different types of myopic maculopathies including macular retinoschisis (MRS).1Hayashi K. Ohno-Matsui K. Shimada N. et al.Long-term pattern of progression of myopic maculopathy: a natural history study.Ophthalmology. 2010; 117: 1595-1611Abstract Full Text Full Text PDF PubMed Scopus (349) Google Scholar Although the exact cause of the MRS has not been determined, we2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar have shown that different types of retinal vascular and paravascular abnormalities detected by optical coherence tomography (OCT) may be related to MRS development. Our High Myopia Clinic was established 34 years ago, and we have performed fluorescein angiography (FA) and OCT on many patients with high myopia. Examination of FA images showed different types of retinal vascular abnormalities, e.g., capillary microaneurysms and capillary teleangiectasia, in many of the highly myopic eyes.This study determined the incidence of retinal vascular abnormalities in highly myopic eyes. We compared the paravascular abnormalities detected by FA to those detected by OCT on a point-by-point fashion. We were especially interested in determining whether the retinal vascular abnormalities detected by FA were correlated with MRS development.Two hundred and thirty-two eyes of 120 consecutive patients with pathologic myopia were prospectively studied. For control, 56 eyes of 56 patients with mild refractive errors (<± 3.0 diopters) were evaluated. Multiple OCT scans (≥30 scans) were performed over the entire extent of the posterior vascular arcade. Three types of FA abnormalities were found; the most frequent was abnormal bending (<60°) of retinal vessels at artery and vein (A-V) crossing in 74.1% (Figure 1; available at http://aaojournal.org), followed by capillary microaneurysms in 27.1% (Figure 2; available at http://aaojournal.org), and capillary teleangiectasia in 23.3% of highly myopic eyes. None of the control eyes had any of these findings. All of the eyes with microaneurysms and teleangiectasia had abnormal bending of retinal vessels in the corresponding area. The FA abnormalities were most frequently detected in the areas of the OCT-determined paravascular abnormalities, e.g., paravascular retinal cysts, vascular microfolds, paravascular lamellar holes, and epiretinal membranes. This was important because these paravascular abnormalities have been shown to contribute to MRS development.2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar The incidence of OCT-determined paravascular abnormalities was significantly higher in eyes with all 3 FA abnormalities than in eyes with only the abnormal bending of retinal vessels (Table 1; available at http://aaojournal.org). In eyes with all 3 of the FA findings, 59.3% of the eyes had paravascular retinoschisis. Macular retinoschisis was detected in 16 eyes by OCT, and all of these eyes had abnormal bending of retinal vessels, and 9 of 16 eyes (56.3%) had both capillary teleangiectasia and microaneurysms. The incidence of MRS increased to 16.7% in the eyes with all 3 FA findings.Table 1Characteristics of highly myopic eyes with bending of retinal vasculature only and with all of 3 angiographic findings (bending of retinal vasculature, capillary teleangiectasia, microaneurysm)Bending of Retinal Vasculature Only (110 Eyes)All of Three FA Findings (54 Eyes)P ValueParavascualr retinal cyst60 (54.5%)43 (79.6%)0.002⁎Chi-square for independence test.Vascular microfolds55 (50.0%)42 (77.8%)<0.001⁎Chi-square for independence test.Paravascular lamellar hole36 (32.7%)27 (50.0%)0.033⁎Chi-square for independence test.Outer retinoschisis37 (33.6%)32 (59.3%)0.002⁎Chi-square for independence test.Inner retinoschisis18 (16.4%)15 (27.8%)0.087Macular retinoschisis7 (6.4%)9 (16.7%)0.037⁎Chi-square for independence test.Epiretinal membrane32 (29.0%)35 (64.8%)<0.001⁎Chi-square for independence test.D = diopter; SD = standard deviation; n.s. = not significant; DA = disc area. Chi-square for independence test. Open table in a new tab Combining these results with those of our earlier studies,2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar we suggest the following mechanism of how retinal vascular abnormalities are related to MRS development. First, when the posterior fundus expands due to an increased axial length or formation of posterior staphyloma, temporal retinal vessels are pulled toward the optic disc. Because of the difference in the flexibility of vascular walls of arterioles and venules, bending of retinal venules develops as the first sign of the expansion of posterior fundus. With time, staphyloma deepens, leading to an increase in the degree of bending of retinal vessels. The increased bending leads to stasis of retinal capillary blood flow peripheral to A-V crossing site, and is observed as capillary microaneurysm and surrounding teleangiectasia by FA. At this stage, more than one-half of the eyes develop vascular microfolds, and have retinoschisis at the site of retinal vessels. Then, MRS develops secondary to the development of paravascular retinoschisis.2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google ScholarIn conclusion, the abnormal FA findings, i.e., abnormal bending of retinal vessels, capillary microaneurysms, and capillary teleangiectasias, correspond to OCT-determined paravascular abnormalities. These changes induce retinal tractional changes especially in eyes with pathological myopia. Therefore, clinicians should carefully search for these vascular abnormalities in FA images, and also for capillary microaneurysms in otherwise healthy highly myopic eyes because they are good signs of an impending MRS. High myopia is a cause of legal blindness worldwide, and the visual impairments are due to different types of myopic maculopathies including macular retinoschisis (MRS).1Hayashi K. Ohno-Matsui K. Shimada N. et al.Long-term pattern of progression of myopic maculopathy: a natural history study.Ophthalmology. 2010; 117: 1595-1611Abstract Full Text Full Text PDF PubMed Scopus (349) Google Scholar Although the exact cause of the MRS has not been determined, we2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar have shown that different types of retinal vascular and paravascular abnormalities detected by optical coherence tomography (OCT) may be related to MRS development. Our High Myopia Clinic was established 34 years ago, and we have performed fluorescein angiography (FA) and OCT on many patients with high myopia. Examination of FA images showed different types of retinal vascular abnormalities, e.g., capillary microaneurysms and capillary teleangiectasia, in many of the highly myopic eyes. This study determined the incidence of retinal vascular abnormalities in highly myopic eyes. We compared the paravascular abnormalities detected by FA to those detected by OCT on a point-by-point fashion. We were especially interested in determining whether the retinal vascular abnormalities detected by FA were correlated with MRS development. Two hundred and thirty-two eyes of 120 consecutive patients with pathologic myopia were prospectively studied. For control, 56 eyes of 56 patients with mild refractive errors (<± 3.0 diopters) were evaluated. Multiple OCT scans (≥30 scans) were performed over the entire extent of the posterior vascular arcade. Three types of FA abnormalities were found; the most frequent was abnormal bending (<60°) of retinal vessels at artery and vein (A-V) crossing in 74.1% (Figure 1; available at http://aaojournal.org), followed by capillary microaneurysms in 27.1% (Figure 2; available at http://aaojournal.org), and capillary teleangiectasia in 23.3% of highly myopic eyes. None of the control eyes had any of these findings. All of the eyes with microaneurysms and teleangiectasia had abnormal bending of retinal vessels in the corresponding area. The FA abnormalities were most frequently detected in the areas of the OCT-determined paravascular abnormalities, e.g., paravascular retinal cysts, vascular microfolds, paravascular lamellar holes, and epiretinal membranes. This was important because these paravascular abnormalities have been shown to contribute to MRS development.2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar The incidence of OCT-determined paravascular abnormalities was significantly higher in eyes with all 3 FA abnormalities than in eyes with only the abnormal bending of retinal vessels (Table 1; available at http://aaojournal.org). In eyes with all 3 of the FA findings, 59.3% of the eyes had paravascular retinoschisis. Macular retinoschisis was detected in 16 eyes by OCT, and all of these eyes had abnormal bending of retinal vessels, and 9 of 16 eyes (56.3%) had both capillary teleangiectasia and microaneurysms. The incidence of MRS increased to 16.7% in the eyes with all 3 FA findings. D = diopter; SD = standard deviation; n.s. = not significant; DA = disc area. Combining these results with those of our earlier studies,2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar we suggest the following mechanism of how retinal vascular abnormalities are related to MRS development. First, when the posterior fundus expands due to an increased axial length or formation of posterior staphyloma, temporal retinal vessels are pulled toward the optic disc. Because of the difference in the flexibility of vascular walls of arterioles and venules, bending of retinal venules develops as the first sign of the expansion of posterior fundus. With time, staphyloma deepens, leading to an increase in the degree of bending of retinal vessels. The increased bending leads to stasis of retinal capillary blood flow peripheral to A-V crossing site, and is observed as capillary microaneurysm and surrounding teleangiectasia by FA. At this stage, more than one-half of the eyes develop vascular microfolds, and have retinoschisis at the site of retinal vessels. Then, MRS develops secondary to the development of paravascular retinoschisis.2Shimada N. Ohno-Matsui K. Nishimuta A. et al.Detection of paravascular lamellar holes and other paravascular abnormalities by optical coherence tomography in eyes with high myopia.Ophthalmology. 2008; 115: 708-717Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar In conclusion, the abnormal FA findings, i.e., abnormal bending of retinal vessels, capillary microaneurysms, and capillary teleangiectasias, correspond to OCT-determined paravascular abnormalities. These changes induce retinal tractional changes especially in eyes with pathological myopia. Therefore, clinicians should carefully search for these vascular abnormalities in FA images, and also for capillary microaneurysms in otherwise healthy highly myopic eyes because they are good signs of an impending MRS. AppendixFigure 2Representative case with a bending of retinal venule at retinal artery and vein crossing sites, and a formation of retinal capillary microaneurysm and retinal capillary teleangiectasia. Right fundus of a 42-year-old woman with a refraction of –14.0 diopters and axial length of 28.5 mm. A, Fluorescein angiogram shows a marked bending of retinal venule at an A-V crossing site in the area between the myopic conus and the central fovea. Many retinal capillary microaneurysms are observed in this area (arrows). Retinal capillary teleangiectasias are also observed in the same area. B, Optical coherence tomography scan along a vertical line in Figure A shows a retinal thickening in the area between the myopic conus and the central fovea.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Long-term Pattern of Progression of Myopic Maculopathy: A Natural History StudyOphthalmologyVol. 117Issue 8PreviewTo investigate the long-term progression pattern of myopic maculopathy and to determine the visual prognosis of each progression stage. Full-Text PDF