Ophthalmology is the specialty in charge of the diagnosis, treatment and prevention of diseases related to vision. Technological advances have allowed a multitude of diagnostic and surgical techniques to solve many visual problems with satisfactory results. Dr. Gegúndez, a reference in the specialty, explains them.
The definition of visual quality is directly associated with concepts such as quality of life or well-being and the increase in life expectancy highlights very frequent eye diseases such as cataracts, macular degeneration or dry eye. Nowadays, glaucoma, diabetic retinopathy or amblyopia, potential causes of blindness, can be detected early. Advances in basic and clinical research and technology make it possible to solve multiple problems and, consequently, cause great social impact and pressure on health care.
Complexities of Ophthalmology derived from the anatomical and functional specificity of the visual apparatus
The foundations of Ophthalmology lie in its great specificity and the necessary division of labor. It is prodigious that a space as small as the eye can contain so much functional and morphological complexity, which requires sophisticated diagnostic means and microsurgical techniques. To put this knowledge into practice requires many years of training and continuous updating. The knowledge of the specialties has expanded in such a way that today it is unaffordable for a single professional. As a result, there are currently subspecialists in retina, uvea, cornea or glaucoma.
What is the current focus of research in Ophthalmology?
The main lines of research focus on treating macular degeneration and other retinopathies with anti-VEGF, as well as on the physiopathology of dry eye and tear substitutes; gene therapy for retinitis pigmentosa; etiology, early diagnosis and new drugs for glaucoma; treatment of uveitis with anti-TNF antibodies and intraocular release devices; improvements in lasers and refractive surgery techniques; microincision cataract surgery (MICS); presbyopia surgery; lamellar transplants of cornea, limbus and retinal tissue; stem cell therapy; factors that determine the development and progression of myopia; and machine vision research.
What is uveitis and what advances are being made to diagnose and treat it?
Uveitis is the inflammation of the uvea -the middle tunica of the eye formed by the iris, ciliary body and choroid- and includes many diseases caused by an endogenous (autoimmune) or exogenous (basically infectious) mechanism. Uveitis is an important cause of blindness in developed countries. In recent years, techniques such as PCR, cytology, serology, ocular biopsies and imaging techniques such as optical coherence tomography (OCT), indocyanine green angiography and ultrasonic biomicroscopy have been incorporated to diagnose uveitis. In terms of treatment, new immunomodulatory drugs, anti-TNF biological agents, intraocular corticosteroid-releasing devices and infravitreal anti-VEGFs stand out.
Cataract surgery is gaining prominence in Ophthalmology. What relevant advances have been made in this procedure?
This surgery offers a high level of complexity, safety and efficacy. By means of microincisional phacoemulsification (MICS), cataracts can be removed and intraocular lenses implanted with incisions of less than 1.8mm. The development of new ultrasound equipment, lenses and micro-instruments, together with the current phaco-refractive surgical techniques, topical anesthesia and sedation, make it possible to provide immediate visual recovery and practically no postoperative recovery, but also to go beyond their own curative purposes and neutralize the previous refractive defect to the point of achieving emmetropia, that is, the complete reduction of myopia, hyperopia or astigmatism.
Is there still no effective treatment for cataracts?
Although the pathophysiological mechanisms and biochemical alterations by which senile cataracts develop are fairly well understood, there is still no pharmacological treatment available. Six years ago I began to study the response of human crystallins to the action of certain proteolytic enzymes and mucopolysaccharidases in order to dilute them or cause variations in their transparency, but the results were disappointing.
What problems can refractive surgery solve today?
The correction of refractive defects (myopia, hyperopia and astigmatism) using excimer lasers has been a real revolution in ophthalmology, making it possible to reduce dependence on glasses or eliminate them completely. The latest generation lasers have been improving in precision and safety, and nowadays there is a wide range of techniques with different indications. In this sense, corneal procedures are performed to correct up to 8 diopters of myopia, 6 of hyperopia and 5 of astigmatism; and others on the crystalline lens that can neutralize major defects by implanting phakic lenses or removing the transparent crystalline lens and replacing it with monofocal, multifocal, toric or pseudoaccommodative lenses, depending on the case. There are other techniques, such as intrastomal rings for keratoconus and mild myopia with risk of ectasia, and corneal or limbal incisions that can be performed during cataract surgery to correct small astigmatisms.
And in which cases is vitreoretinal surgery indicated?
Technologies such as 23-25 G vitrectomy, Xenon light sources, endolasers, high precision microinstruments, wide field lenses, expandable gases, perfluorocarbon compounds and vitreous substitutes have improved the prognosis of retinal detachments, vitreous hemorrhages, proliferative diabetic retinopathies, ocular trauma or complications of cataract surgery. Vitrectomy also makes it possible to treat epiretinal membranes or macular hole.
Solving presbyopia, what are the innovations in this regard?
Presbyopia or eyestrain is the loss of accommodation capacity of the crystalline lens to modify its curvature and focus at different distances. It usually develops after the age of 40. The treatments that have so far shown efficacy are the implantation of multifocal or pseudoaccommodative intraocular lenses, alternating monovision (correcting one eye for distance and the other for near) and multifocal corneal carving using excimer laser. However, none of these techniques is able to restore physiological accommodation. What they do is reduce or cancel the effects of presbyopia on near vision, but they are not free of undesirable effects such as loss of luminous sensitivity or the appearance of night halos. If we add to this a non-optimized risk/benefit ratio, we are faced with a set of techniques that, for the time being, cannot be considered universally applicable.
Macular degeneration (AMD) is the greatest challenge in ophthalmology. Is prevention essential? What role do anti-angiogenic drugs play in its treatment?
The treatments that have so far shown efficacy are the implantation of multifocal or pseudoaccommodative intraocular lenses, alternating monovision (correcting one eye for distance and the other for near) and multifocal corneal carving using excimer laser. However, none of these techniques is able to restore physiological accommodation. What they do is reduce or cancel the effects of presbyopia on near vision, but they are not free of undesirable effects such as loss of luminous sensitivity or the appearance of night halos. If we add to this a non-optimized risk/benefit ratio, we are faced with a set of techniques that, for the time being, cannot be considered universally applicable.
In the early stages of AMD, retinal photoreceptors begin to accumulate waste metabolites in the retina, causing deposits or drusen. As the disease progresses, abnormal blood vessels form, causing hemorrhages, edema and loss of central vision. If left untreated, the photoreceptors will be replaced by scar tissue and visual loss will be irreversible. In addition to aging, cardiovascular disease, the effect of solar radiation, tobacco and alcohol consumption and, occasionally, previous intraocular surgery have been implicated. Prevention is fundamental, eliminating or treating the aforementioned factors, incorporating moderate exercise together with a balanced diet and undergoing periodic fundus examinations. Many ophthalmologists add vitamin and mineral supplements, although their preventive efficacy is not shared by the entire scientific community. When AMD begins to progress and show symptoms, action must be taken without delay. Its better prognosis will depend on this. The most effective treatment to date has been intravitreal injections of antiangiogenic drugs which, in the earliest cases, can slow down or even partially reverse visual deterioration.
Advances in the early diagnosis of glaucoma
New technologies have been introduced in the field of diagnosis, such as optical coherence tomography (OCT), laser polarimetry (GDx) and scanning laser ophthalmoscopy (HRT). To this must be added the use of more powerful ocular hypotensive drugs (f2-alpha prostaglandins), pharmacological associations that allow better control and compliance with treatments and techniques such as non-perforating surgery, valve implants and trabecular stents. Today, thanks to better information, campaigns and collective awareness, ocular hypertension and glaucoma can be detected early, making it possible to avoid or slow down the deterioration of the visual field.
What advances are there in the diagnosis and treatment of corneal and ocular surface diseases?
The study of the pathophysiological mechanisms that cause ocular surface alterations in the “dry eye” syndrome stands out. A better understanding of these mechanisms allows us to apply more effective artificial compounds, tear substitutes. On the other hand, new drugs have been introduced for topical use against external ocular infections, recurrent alterations of corneal regeneration and autoimmune diseases of the eye surface. New corneal reconstruction techniques have also been developed, such as lamellar keratoplasty, limbal transplantation, amniotic membrane and cross-linking for keratoconus and other corneal ectasias.
Is advanced technology today the ophthalmologist’s best ally?
It is true that ophthalmology depends on technical advances, but we must not forget that we are doctors and that we deal with people, not machines. We must prioritize the perceived quality and the more humanistic Hippocratic values of the profession, not only the knowledge and scientific-technical quality that, a priori, are assumed of a doctor, especially in Spain, where the level of medicine is excellent. Our ability to generate security and trust continues to be the best ally to promote peace of mind and satisfaction. And conversely, the greatest joy for a doctor will be to obtain the recognition of patients. I am fortunate to be able to count, at the Sanitas La Moraleja Hospital, on a team of professionals of great scientific and human quality, with the same philosophy.
What applications can stem cells have in ophthalmology in the future?
The implantation of adult stem cells from the limbic epithelium is already being tested in humans in order to regenerate the cornea in cases of insufficiency and loss of transparency due to different causes. Stem cells are also being investigated to regenerate iris and retina in aniridia and retinitis pigmentosa, although no clear conclusions have yet been reached on the latter.
Will artificial vision arrive?
In the United States, certain extraocular devices have already been tested that are capable of transmitting electrical impulses to the cerebral cortex and being processed in the form of a certain degree of visual perception, albeit very rudimentary. At the same time, the feasibility of implanting an intraocular “chip” in the retina, equipped with photodiodes that, receiving the signal from the outside through special glasses, would send electrical impulses to the occipital cortex through the optic nerve, thus inducing the formation of images, is being studied.