Retinal screenings

Overview of Treatment

Retinal screening is a diagnostic procedure used to assess the health status of the retina, primarily through specialized equipment observing the retinal blood vessels, nerve layers, and macular structures. The purpose of this examination is to detect early potential lesions such as diabetic retinopathy, glaucoma, and age-related macular degeneration, thereby enabling the formulation of preventive treatment plans. Unlike therapeutic medical interventions, retinal screening belongs to preventive medicine, effectively reducing the risk of permanent vision loss.

Using high-resolution imaging technology, physicians can immediately identify signs such as microaneurysms, retinal hemorrhages, or nerve cell atrophy. This procedure is usually a necessary component of regular follow-up for patients with chronic diseases, especially among diabetics, reducing the risk of vision impairment by over 60%. Regular screening allows early intervention, preventing progression to irreversible stages.

Types and Mechanisms of Treatment

Retinal screening includes a combination of techniques:

• Fundus examination: direct observation of retinal blood vessels and nerve layers by the physician
• Optical Coherence Tomography (OCT): laser light measurement of retinal layer thickness
• Choroidal angiography: injection of contrast agent to track blood flow

These technologies collectively create three-dimensional images, assisting physicians in accurately assessing the severity of lesions.

Mechanistically, OCT uses near-infrared light to penetrate tissues, allowing micron-level structural differentiation, while fluorescein angiography can reveal vascular leakage and blockages. Integrating these data helps predict risks such as macular edema or retinal detachment, thereby guiding treatments like laser therapy or anti-VEGF injections.

Indications

Mainly suitable for high-risk groups:

• Patients with a history of diabetes for over 5 years
• Patients with hypertension or hyperlipidemia
• Individuals with a family history of retinal detachment
• Patients on long-term steroid therapy

These groups have a 3-5 times higher risk of retinal lesions due to fragile microvasculature or abnormal blood circulation.

Additionally, for those over 40, comprehensive screening is recommended every 2 years, and annually for those over 60. Patients who have undergone cataract surgery need to re-establish baseline measurements to compare pre- and post-operative changes.

Usage and Dosage

The examination process consists of three stages:

1. Pupil dilation: using cycloplegic agents (such as mydriatics) to enlarge the pupils
2. Imaging capture: using digital photography or scanners for 15-20 minutes
3. Report analysis: interpreted by specialist physicians for abnormalities

This non-invasive design makes the procedure painless and safe.

Screening frequency is adjusted based on risk levels:

• Early-stage diabetic patients: once a year
• Patients with mild lesions: once every 6 months
• High-risk glaucoma groups: combined with intraocular pressure testing every 3-6 months

Patients with mobility issues can opt for home-based simple screening kits, though their accuracy only reaches 70-80% of medical-grade standards.

Benefits and Advantages

Main benefits include:

• Early detection of reversible lesions
• Reducing the risk of 90% of vision loss
• Shortening treatment decision times

Research by the Taiwan Diabetes Association in 2023 shows that regular screening allows laser treatment to be initiated on average 14 months earlier, increasing success rates by 35%.

Advantages are:

• Non-invasive testing
• Ability to monitor disease progression
• High correlation with other tests such as visual field testing

Results can be critical for surgical planning, such as laser targeting for macular edema treatment.

Risks and Side Effects

Main risks include:

• Photophobia after pupil dilation (lasting 4-6 hours)
• Allergic reactions to dilation agents in 0.3% of patients
• Elevated intraocular pressure potentially triggering acute glaucoma in susceptible individuals

Some cases may experience temporary blurred vision, usually resolving within 24 hours.

Serious complications are extremely rare, including allergic reactions to contrast agents (incidence 0.02%) or thermal damage to retinal tissue from laser (less than 0.01%). Prior to contrast injection, patients should be checked for allergies to iodine or iodine-containing contrast media.

Precautions and Contraindications

Contraindications include:

• Severe glaucoma attack
• Heart or kidney failure preventing contrast agent metabolism
• Severe cataracts affecting vision

Pregnant women should evaluate fetal risks before contrast injection; non-invasive OCT is recommended instead.

Before the examination, note:

• Avoid caffeine drinks 2 hours prior
• Bring sunglasses due to photophobia after dilation
• Diabetic patients should control blood sugar below 150 mg/dL

Special populations such as those with severe dry eye should inform medical staff in advance.

Interactions with Other Treatments

Examination results directly influence treatment choices:

• Microvascular leakage → laser photocoagulation
• Macular edema → anti-VEGF injections
• Optic nerve compression → intraocular pressure-lowering medications for glaucoma

Screening data can be cross-verified with retinal electroretinography (ERG) results to improve diagnostic accuracy.

Relation to surgical treatments: Pre-cataract surgery screening can assess the feasibility of intraocular lens implantation in the posterior chamber, while post-operative follow-up can evaluate the risk of retinal detachment. Patients undergoing anti-VEGF therapy should have retinal structure monitoring every 3 months.

Effectiveness and Evidence

Large studies show that regular screening reduces the blindness rate of diabetic retinopathy by 58%. The American Academy of Ophthalmology (AAO) recommends annual screening for type 2 diabetics from diagnosis, reducing the risk of severe retinal disease by 73%.

The 2022 Lancet study indicates that combined OCT and adaptive optics screening systems can detect micro-lesions as small as 0.1mm with an accuracy of 97.6%. These data provide an objective basis for personalized treatment plans.

Alternatives

Non-medical grade alternatives:

• Home vision testing cards (accuracy 60-70%)
• Automated retinal cameras (requiring remote interpretation by physicians)

but cannot replace professional immediate diagnosis.

Medical alternative procedures:

• Electrophysiological testing of the retina (ERG/EOG)
• Ultrasound biomicroscopy

but these methods have lower sensitivity for microvascular lesions and are usually supplementary tests.

 

Frequently Asked Questions

What preparations are needed before the examination? Is fasting or medication cessation required?

Usually, no fasting is necessary before retinal screening, but if pupil dilation is involved, it is recommended to avoid taking medications that may affect pupil constriction (such as certain antihistamines) 4 hours prior. Patients with diabetes or high myopia should inform medical staff in advance to adjust the examination method.

Will the examination cause discomfort or pain in the eyes?

Generally, retinal screening is painless, but pupil dilation may cause temporary photophobia or blurred vision, which usually resolves within 4 to 6 hours. Using ophthalmoscopy or OCT only requires keeping the head steady and avoiding rapid eye movements, with no pain involved.

What should be done if abnormal symptoms occur after the examination?

If severe photophobia or blurred vision persists beyond 8 hours after dilation, or if eye pain or headache occurs, immediate medical attention is advised. It is recommended to wear UV-protective sunglasses when going out and avoid driving alone, as vision may not be fully recovered.

How often should screening be performed at different ages?

Individuals under 40 without a family history should be screened every 2-3 years; those over 40 or with diabetes are advised to have annual exams; high myopia (over 600 degrees) should be followed every 6-12 months. High-risk groups such as retinopathy of prematurity should follow personalized schedules as prescribed by their physicians.

What are the possible follow-up treatments if abnormalities are detected?

If retinal tears or macular lesions are found, laser photocoagulation or cryotherapy may be recommended; severe diabetic retinopathy may require anti-VEGF injections or vitrectomy. All treatment plans are tailored based on lesion severity and overall health status.