Glassblower's Cataract

Glassblower's cataract is occupational lens opacity from chronic intense infrared radiation and heat in glassworking. It was historically accompanied by true exfoliation of the anterior lens capsule. It is rare with modern controls.

Exposure. Glassblowing and glass gathering at furnace openings, where molten glass is at 1000 to 1500 degrees Celsius, and bottle and sheet glass making. Disease follows many years of unprotected exposure.

Epidemiology. Historically common in glassworkers after 10 to 20 years of work. It fell with eye protection, enclosed furnaces and shorter exposure. Cases now appear in small workshops and low resource settings.

Appearance. Posterior subcapsular and cortical opacity, often with anterior capsule changes. True exfoliation is a lamellar splitting of the superficial anterior capsule, with a curled membrane in the anterior chamber, and is characteristic but uncommon.

Course. Opacity progresses with continued exposure and may continue slowly after exposure ends.

Pathophysiology.

The lens has no blood supply and dissipates heat poorly. Infrared radiation heats the iris pigment and aqueous humour, and the lens absorbs some directly.

Thermal denaturation of lens proteins and capsule layers produces opacity and capsular delamination.

• Glare, blurred vision, reduced contrast and difficulty in bright light, often bilateral.
• Floating film or flakes in the anterior chamber in exfoliation.
• Eye discomfort from heat and dryness.

Red flags.

• Sudden visual loss, eye pain or a red eye (inflammation, raised pressure, retinal detachment).

• Work history: furnace distance, years, tasks and eyewear.
• Slit lamp examination with dilated pupil and retroillumination, noting capsule exfoliation.
• Visual acuity, glare testing and intraocular pressure.
• Exclude other causes: age, diabetes, steroid use, uveitis, trauma, ionising radiation.
• Baseline and periodic lens examination for exposed workers.

Differential diagnosis. Age related cataract, steroid induced cataract, diabetic cataract, uveitic cataract, ionising radiation cataract, traumatic cataract, pseudoexfoliation syndrome.

• Prevention: infrared absorbing filter lenses with side shields or face shields of suitable shade for furnace work, shorter direct view time, furnace shielding and rest breaks away from the opening.
• Mild opacity: observation, updated glasses and glare management.
• Cataract surgery by phacoemulsification with intraocular lens implantation when function limits work or daily tasks. Warn the surgeon of capsular delamination, because the anterior capsule may be fragile. Postoperative drops and follow up by the operating surgeon.
• No drug treatment prevents or reverses the opacity.

Monitoring. Slit lamp examination every 1 to 2 years in exposed workers, and yearly once opacity is present.

Referral and escalation. Ophthalmology for any lens opacity, visual symptoms or surgery planning; occupational physician for workplace control and compensation where required.