Catálogo de publicaciones - libros

Fluorescein is one of the most potent artificial dyes. It was first synthesized in 1871 by Adolf von Baeyer, a German chemist who in 1905 received the Nobel Prize in chemistry for his work on organic dyes.

Retinal vascular diseases, in particular diabetic retinopathy and retinal venous occlusive disorders, are important causes of visual loss and blindness. Other important retinal vascular diseases which can affect visual function include arterial occlusive disease, parafoveal telangiectasis, Coat’s disease, vasculitides, macroaneurysms, and hypertensive retinopathy. Despite the various etiologies and underlying pathogenic processes, the mechanisms of visual loss are frequently similar among these diseases. One such common final pathway is the development of occlusions of the microcirculation (capillaries) with attendant retinal ischemia. The most frequent sequela, however, is a compromise in retinal vascular permeability leading to leakage and exudation with accumulation of fluid, lipid, and proteins within the retina [ 40 ] or in the subretinal space. Structural alterations are also a frequent outcome of retinal vascular disease. These changes include the development of cystoid spaces in the retina and vitreomacular traction.

Today light coagulation is a common treatment procedure and the basis of treatment in many retinal diseases. Its origins go back to Meyer-Schwickerath 1949 [ 46 ], who initially used sunlight as an energy source. However, sunlight was unsuitable for several reasons. A system of several mirrors and a long exposure time were necessary. The dependence on the weather forecast was an obvious problem. With the development of xenon high pressure lamps (Fig. 13.1) at the beginning of the 1950s, enough power for light coagulation of the ocular fundus became available [ 34 ]. Much scientific work was published at this time which showed the therapeutic effect of the light coagulation and which led to a wider experience [ 47 , 48 ]. The main focuses of clinically based xenon coagulation were retinopexy and the treatment of proliferative diabetic retinopathy.

Photodynamic therapy (PDT) with verteporfin has significantly improved functional outcome in the treatment of choroidal neovascularization (CNV) in various clinical disorders [ 86 ]. While CNV due to age-related macular degeneration [ 4 , 53 , 76 – 80 , 84 ] and pathologic myopia [ 83 , 85 ] was the primary focus, several studies showed that the treatment effects of PDT were not only restricted to these two underlying disorders. Recently, several clinical studies observed PDT as a treatment modality of CNV due to ocular histoplasmosis syndrome [ 52 , 55 , 68 ], choroiditis [ 71 , 89 ], angioid streaks [ 31 , 37 , 68 ], Stargardt’s disease [ 81 ], symptomatic choroidal hemangioma [ 30 , 61 , 82 ] and other causes [ 15 , 72 ]. While PDT has become an established treatment modality for various choroidal disorders, its role in the treatment of retinal diseases remains to be determined.

Cryotherapy has a long history in the treatment of retinal vascular disease. Freezing the retina to create inflammation in the area of application began as early as 1918, when Schöler applied solid carbon dioxide to the sclera and described choroidal inflammation [ 9 ]. In the treatment of proliferative retinopathy, cryotherapy today has largely been replaced by laser photocoagulation. However, the transscleral mode of application renders cryotherapy particularly useful in the case of hazy media or cataracts. It is also useful in treating more peripheral lesions that cannot be easily visualized at a slit lamp.

No advance in the treatment of vitreoretinal diseases has been as significant as the introduction of pars plana vitrectomy by Machemer in 1971 [ 44 ]. The closed system allowed for a safe intraocular manipulation and constant viewing of the retina. During the past few decades the instrumentation has advanced, but the same principles still apply.

In most cases (97%) neovascular glaucoma is caused by ischemia [ 5 ]. The most common underlying diseases are proliferative diabetic retinopathy and proliferative retinopathy after central retinal vein occlusion (CRVO). Rare types of neovascular glaucoma are of non-ischemic nature (e.g., tumor-induced, inflammatory disease) but should be separated because of different treatment strategies (Table 17.1).

Intravitreal injection was reported by Ohm in 1911 as a technique to introduce air for retinal tamponade and repair of retinal detachment [ 28 ]. Intravitreal administration of pharmacotherapies dates to the mid-1940s with the use of penicillin to treat endophthalmitis [ 34 , 35 ]. Since that time, use of the intravitreal injection technique has steadily increased, with its usage being focused primarily on the treatment of retinal detachment [ 7 , 32 ], endophthalmitis [ 8 , 31 ], and cytomegalovirus (CMV) retinitis [ 13 , 43 ]. The increasing confidence in the efficacy and safety of intravitreal injections, in conjunction with the development of additional pharmacotherapies, has led to a recent rapid increase in the use of this technique for the administration of various pharmacotherapies (e.g., ranibizumab [ 6 ], pegaptanib sodium [ 9 , 41 , 42 ]) for age-related macular degeneration (AMD) and intravitreal triamcinolone for macular edema associated with a variety of etiologies, such as diabetic retinopathy [ 21 ], central retinal vein occlusion [ 10 , 36 ], branch retinal vein occlusion [ 5 , 17 , 30 , 37 ], uveitis [ 2 , 44 ], and birdshot retinochoroidopathy [ 22 ].

The grading of diabetic retinopathy is based on the concept that a hierarchy of stages can be defined, where the higher the grade, the higher the risk of suffering visual loss. The grading scale reflects the natural course of the disease in its unrelenting and most devastating form. In reality, diabetic retinopathy can regress both spontaneously and after therapeutic intervention. To construct or validate a grading scale, rates of progression to visual loss or another endpoint that is meaningful to the patient must be measured. Grading scales constructed for scientific and regulatory purposes, such as the study of new interventions, are made with the purpose of achieving maximum sensitivity for change in retinopathy. Interventional trials may then result in selected grades being validated and found useful for guiding interventions such as photocoagulation for proliferative diabetic retinopathy or diabetic macular edema. The timely identification of patients who reach interventional thresholds is the purpose subserved by simpler grading scales used in clinical screening practice.

Retinopathy of prematurity (ROP) was first noted in the late 1940s in preterm infants and described as retrolental fibroplasia, a total retinal detachment seen as white mass behind the lens. The disease was subsequently associated with excessive oxygen use [ 12 , 14 , 52 ]. Oxygen supplementation was curtailed with a decrease in ROP but with an increase in cerebral palsy and death. Supplemental oxygen is now delivered to premature infants to maintain adequate blood levels, but it is monitored carefully [ 37 ].