Diabetic retinopathy: why vision suddenly falls and how to catch it in time in Tashkent

What diabetes does to the retinal vessels

Long-term elevated glucose levels damage the walls of the smallest vessels - capillaries. In the retina, their network is especially dense and especially vulnerable. First, the supporting cells of the capillary wall die, and the vessel loses its tone: microaneurysms appear - tiny saccular protrusions that are visible to the doctor as red dots in the fundus. The wall becomes permeable, and through it plasma and fats leak into the retinal tissue - edema and dense yellow deposits are formed. In this case, some of the capillaries close completely, and areas of the retina remain without blood flow.

Then the mechanism turns on, which leads to disaster. The bloodless areas of the retina secrete substances that stimulate the growth of new blood vessels - the body is trying to improve nutrition. But the newly formed vessels are defective: they are fragile, grow in the wrong place, grow into the vitreous body and rupture easily. Their rupture causes hemorrhage, and vision disappears literally instantly. Scar tissue forms around such vessels, which contracts and tightens the retina, tearing it away from the wall of the eye. It is at this stage that diabetes completely takes away vision.

• Microaneurysms and pinpoint hemorrhages are the earliest visible changes
• Hard exudates - yellow deposits of lipids in the retina
• Swelling of the retina due to fluid leaking through the damaged vessel wall
• Areas completely devoid of blood flow are a source of signal for the growth of new vessels
• Newly formed vessels are fragile and easily bleed into the vitreous body
• Scar cords that tighten the retina and cause tractional detachment

Why does vision remain good for a long time?

This is a key point that explains the whole logic of monitoring for diabetes. Visual acuity is formed by a tiny area of ​​the retina in the very center - the macula, or rather its central fovea, which is less than two millimeters in size. The rest of the huge field of the retina is responsible for lateral vision and orientation in space, where small details are not important. Diabetic changes begin in the periphery and can exist there for years without affecting the ability to read. A person checks his vision using a table, sees the tenth line and concludes that everything is fine with his eyes.

• The periphery of the retina can be significantly affected, while visual acuity remains complete
• The first complaints often appear already at the stage when laser treatment or injections are required
• A sudden drop in vision usually does not mean the onset of the disease, but its complication - hemorrhage or detachment
• The exception to the rule is macular edema: it affects the center and therefore gives symptoms early, but can occur at any stage
• Good visual acuity does not eliminate the need to examine the fundus with a dilated pupil

This is where the most common objection from patients comes from: “I can see well, why do I need to see an ophthalmologist.” A chart check and a fundus examination are two fundamentally different procedures that answer different questions. The table shows how the center of the retina is working right now. Examination with a wide pupil shows what is happening throughout its entire area, and allows you to see the problem years before complaints appear. Checking your vision at the optics for diabetes is not enough, and this should be taken literally: without drops and examination of the periphery, the examination would not take place.

Stages and what they mean in practice

1. Непролиферативная стадия. На глазном дне видны микроаневризмы, точечные кровоизлияния, иногда твёрдые экссудаты. Зрение обычно нормальное. Задача этого этапа — контроль сахара, давления и липидов, а также регулярное наблюдение.
2. Препролиферативная стадия. Изменений становится намного больше, появляются признаки выраженного кислородного голодания сетчатки: множественные кровоизлияния, изменённые вены, мягкие очаги. Это стадия, на которой обсуждают лазерное лечение, поскольку риск перехода в следующую велик.
3. Пролиферативная стадия. Растут новообразованные сосуды — на сетчатке, диске зрительного нерва, иногда на радужке. Именно они дают кровоизлияния в стекловидное тело и тракционную отслойку. Treatment необходимо и откладывать его нельзя.
4. Терминальные осложнения: обширные рубцовые изменения, тракционная отслойка сетчатки, вторичная неоваскулярная глаукома — состояние, при котором сосуды прорастают в угол передней камеры и внутриглазное давление становится очень высоким и болезненным.
5. Диабетический макулярный отёк выделяют отдельно: скопление жидкости в центре сетчатки. Он способен развиться на любой стадии, в том числе на самой ранней, и именно он чаще всего снижает зрение у людей с диабетом 2 типа.

Inspection Schedule: Basic Rule of Thumb

It is the schedule, not complaints, that determines whether vision can be preserved. It differs between the two types of diabetes because the timing of the onset of the disease differs: in type 2, diabetes often exists for several years before it is found, and retinopathy can be detected already at diagnosis.

• Diabetes mellitus type 1: first fundus examination approximately 5 years after the onset of the disease, and in adolescents - with the onset of puberty; further annually
• Diabetes mellitus type 2: first examination immediately upon diagnosis, since changes may already be present; further annually
• If changes are detected, the frequency of examinations increases to once every 3-6 months according to the doctor’s decision
• Pregnancy with existing diabetes: examination during planning, then in each trimester and after childbirth - pregnancy can dramatically accelerate the progression
• Gestational diabetes that first appears during pregnancy does not usually carry such a risk and does not require such a regime of examinations
• Any sudden deterioration in vision is a reason to contact immediately, out of schedule

There is a paradox that patients with very high sugar are always warned about. A sharp decrease in glucose levels in a matter of weeks after many years of decompensation sometimes causes a temporary worsening of retinopathy. This does not mean that you do not need to reduce sugar - in the long term, good control definitely benefits and protects the retina. This means something else: before starting intensive treatment for diabetes, it is worth examining the fundus of the eye and observing it more often in the first year. This is especially true for people with a long history of poorly controlled diabetes who are prescribed insulin or new treatment regimens.

Examination and treatment

1. Проверка остроты зрения и измерение внутриглазного давления.
2. Осмотр глазного дна с широким зрачком — базовое исследование, определяющее стадию.
3. Оптическая когерентная томография — послойный срез сетчатки; главный метод выявления и контроля макулярного отёка, показывает его в микрометрах толщины.
4. Фотографирование глазного дна — фиксирует картину для сравнения при следующих визитах.
5. Флюоресцентная ангиография сетчатки — выявляет зоны без кровотока и новообразованные сосуды, помогает спланировать лазерное лечение.
6. Ультразвуковое исследование глаза — при кровоизлиянии в стекловидное тело, когда сетчатку не рассмотреть.
7. Совместно с эндокринологом — гликированный гемоглобин, липидный профиль, оценка функции почек, контроль артериального давления.

Treatment is selected according to stage. Panretinal laser coagulation - applying multiple laser points along the periphery of the retina - reduces the production of signals for vascular growth and causes newly formed vessels to regress; This is a method that has been saving eyes during the proliferative stage for decades. Intravitreal injections of drugs that suppress vascular growth are injected directly into the eye cavity and are used primarily for macular edema, and also as an addition to laser; they require repeated administrations according to the scheme, and they cannot be skipped. In case of hemorrhage that does not resolve, and in case of tractional detachment, vitrectomy is performed - removal of the altered vitreous body with straightening of the retina. Separately, long-acting steroid implants are used for persistent edema.

What depends on the patient himself

1. Контроль уровня глюкозы: именно он определяет скорость развития ретинопатии сильнее всех прочих факторов. Ориентир по гликированному гемоглобину устанавливает эндокринолог индивидуально.
2. Контроль артериального давления — по значимости для сетчатки он идёт сразу за сахаром, а при уже имеющейся ретинопатии не уступает ему.
3. Контроль липидов крови: высокий уровень жиров связан с образованием твёрдых экссудатов в макуле.
4. Полный отказ от курения — оно многократно усиливает повреждение мелких сосудов.
5. Соблюдение графика осмотров глазного дна даже при отличном самочувствии и полной остроте зрения.
6. Наблюдение у нефролога при появлении белка в моче: поражение почек и сетчатки идут рука об руку.
7. Немедленное обращение при внезапном ухудшении зрения, появлении плавающих чёрных точек или пелены.
8. Осторожность с интенсивными нагрузками с натуживанием при пролиферативной стадии — их объём стоит обсудить с офтальмологом.