Types of Cataracts: A Comprehensive Guide to Classification by Location, Cause, and Their Impact on Vision
- sakai208
- Nov 11, 2025
- 4 min read
I. Introduction: Why Understanding Cataract Types is Essential
When an ophthalmologist diagnoses a cataract, the conversation extends far beyond the fact that the lens is cloudy. Cataracts are diverse, and their appearance, location, and underlying cause are critical factors that directly influence the patient's specific visual symptoms, the surgical technique employed, and the choice of the appropriate Intraocular Lens (IOL).
Understanding the different types of cataracts is essential for any patient considering surgery. This article provides a comprehensive guide to classifying cataracts based on both anatomical location and cause, detailing why the meticulous diagnostic approach utilized by Japanese specialists is crucial for tailoring treatment to maximize visual clarity and safety.
II. Classification by Location (Anatomical)
The location of the opacity within the crystalline lens is the most clinically important classification, as it dictates the symptoms the patient experiences and the complexity of the surgery.
1. Nuclear Cataract (NC):
Location: Occurs in the center, or nucleus, of the lens.
Effect: This type causes the lens to harden (sclerosis) and often turn a yellowish or brownish color. It leads to progressive diminution of distant vision and can cause a temporary refractive shift toward nearsightedness (myopia).
Surgical Note: The hardness of the nucleus dictates the required amount of ultrasonic energy (phacoemulsification energy) during surgery.
2. Cortical Cataract (C):
Location: Develops in the lens cortex, or the outer layer, often manifesting as wedge-shaped opacities that point towards the center.
Effect: Because the opacities are separated by clear areas, they scatter light easily. This results in significant glare, light sensitivity, and halos, which are particularly bothersome in low-light conditions (e.g., night driving).
3. Posterior Subcapsular Cataract (PSC):
Location: Forms on the back surface of the lens, directly beneath the posterior capsule.
Effect: This is the most symptomatic type in its early stages because the opacity is directly in the central visual axis. Symptoms are drastically worsened by pupil constriction (e.g., in bright sunlight or when reading), leading to severe difficulty with reading and fine detail work.
III. Classification by Cause (Etiological)
While most cataracts are related to aging, the underlying cause can influence the patient's overall health management.
1. Age-Related (Senile Cataracts): This is the most common category, occurring as a natural consequence of protein breakdown and aggregation in the lens over time.
2. Secondary Cataracts: These cataracts develop as a consequence of other systemic diseases or medical treatments:
Diabetes: Poorly controlled diabetes is a major risk factor, often leading to rapid cataract progression.
Medications: Long-term, high-dose use of corticosteroids (steroids) is a well-known cause.
Ocular Diseases: Conditions like chronic uveitis (intraocular inflammation) can accelerate cataract formation.
3. Traumatic Cataracts: Caused by blunt force or penetrating injury to the eye. The resulting opacities can be localized or diffuse and often develop rapidly.
4. Congenital Cataracts: Cataracts present at birth or developing shortly thereafter, often due to genetic factors or infectious diseases during pregnancy.
IV. Impact of Type on Symptoms and Surgical Strategy
The anatomical type of cataract is crucial not only for symptom assessment but for determining the safest and most effective surgical solution.
1. Type Dictates Symptoms: The correlation is clear: A patient with a dominant Cortical Cataract is more likely to complain of blinding glare while driving at night, while a patient with a dominant Posterior Subcapsular Cataract (PSC) is more likely to complain of difficulty reading in the daytime.
2. Surgical Technique: The degree of Nuclear Sclerosis (hardness) determines the surgical strategy. A harder nucleus necessitates the use of a Femtosecond Laser (FLACS) or specialized phaco-techniques to reduce the high energy required, thereby protecting the delicate corneal endothelial cells.
V. The Japanese Diagnostic Precision
The confidence in recommending surgery and selecting the perfect IOL is built on the precision of the diagnosis.
1. Meticulous Documentation: Japanese medical standards require precise, standardized documentation of the types of cataracts using classification systems (such as LOCS III or hardness-based systems) and highly detailed anterior segment imaging. This meticulous recording ensures consistency and allows the entire surgical team to accurately predict the complexity of the nucleus and cortex.
2. Customized IOL Planning: Japanese specialists do not rely on a single data point. They integrate information from anatomical location (to predict glare risk), nuclear hardness (to predict energy use), and the patient's lifestyle. This integration ensures that the final IOL choice—whether advanced multifocal or a highly precise monofocal—is perfectly suited for the patient's specific cataract type and visual demands.
3. Risk Stratification: The detailed classification process serves as an important risk stratification tool. By understanding the specific type of opacity, the specialist can provide the patient with a highly accurate prediction of post-operative healing and potential side effects.
VI. Conclusion: Precision Diagnosis Leads to Optimal Outcomes
Understanding the various types of cataracts is essential for successful treatment. It is the complex interplay of the cataract's anatomical location and its hardness that defines the difficulty of the surgery and the best choice of IOL.
By choosing the diagnostic precision and meticulous standards of Japanese ophthalmology, patients benefit from experts who classify, measure, and plan with unparalleled detail. This commitment to precise classification ensures the safest surgical execution and the highest probability of a tailored visual outcome, confirming the superior quality of care available in Japan.
This article was reviewed by
Dr. Daiki Sakai, MD
