What does the term cataracta nigra describe?

A brunescent nucleus that has become almost black Cataracta nigra is the name given to the most extreme stage of a brunescent cataract, in which the deep brown nucleus has become almost black.

A cataract with a white mature cortex

A congenital pigmented lens opacity

A lens darkened by intraocular haemorrhage

What is the second sight reported by some patients developing a brunescent cataract?

Temporarily improved near vision from a myopic shift A myopic shift can improve near vision for a time, but this second sight gradually lessens as the nucleus darkens further.

Restored colour vision in bright light

Return of normal contrast sensitivity

Better night vision once glare settles

Why is the corneal endothelium especially at risk during surgery on a brunescent cataract?

More ultrasound energy generates heat and turbulence A hard nucleus needs more ultrasound energy to emulsify, and the resulting heat and turbulence put the corneal endothelium at risk.

The anterior chamber is unusually shallow

The lens leaks toxic protein into the aqueous

Pupil dilation is always inadequate

Which step helps achieve a capsulorhexis when the red reflex is poor in a dense cataract?

Trypan blue staining of the anterior capsule A dull or absent red reflex makes the capsulorhexis harder, so trypan blue staining of the anterior capsule is often necessary.

Raising the irrigation bottle height

Injecting intracameral adrenaline

Which preoperative test assesses endothelial reserve before surgery on a hard nucleus?

Specular microscopy Preoperative specular microscopy is used to assess the endothelial reserve, alongside planning such as the soft shell technique and low-energy nuclear disassembly.

When should manual small incision cataract surgery be considered for a brunescent cataract?

When the nucleus is very dense and the endothelium poor Manual small incision surgery or extracapsular extraction is considered when the nucleus is very dense and the endothelium is poor, particularly where phaco resources are limited.

In every patient over the age of seventy

Only when the posterior capsule is already open

When a multifocal lens is planned

Which investigation is essential when a dense brunescent lens hides the fundus?

B-scan ultrasound Because a dense lens hides the fundus, B-scan ultrasound is essential to exclude a retinal detachment, a tumour or a staphyloma before surgery.

What is the best strategy for avoiding the higher surgical risk of a brunescent cataract?

Earlier surgery before the nucleus hardens Visual results can be excellent when the retina and optic nerve are healthy, but complication rates are higher, so the best strategy is surgery before the nucleus becomes so hard.

Repeated laser treatments to the lens

Topical therapy to soften the nucleus

Waiting until vision is light perception only

Brunescent Cataract: Planning Surgery for a Hard Nucleus

A brunescent cataract is an advanced nuclear cataract in which the nucleus has changed from yellow to deep brown, and, in the most extreme cases, to almost black.

The name cataracta nigra is used for this last stage.

These lenses are hard, and they are the ones that surgeons approach with the most caution.

Why the nucleus darkens

Throughout life, the nucleus of the lens becomes denser and more compact, as new fibers are laid down around the old ones.

Proteins in the nucleus aggregate and are modified by oxidation, glycation, and ultraviolet exposure, and they become cross-linked and pigmented.

The progression is from clear, to yellow, to amber, to brown, and finally to black.

Patients who have lived in tropical, high-altitude and high-UV environments, those who smoke, and those with diabetes and long-standing steroid use develop brunescence earlier.

In places where cataract surgery is delayed for economic or access reasons, brunescent cataracts are seen much more often than in places with early surgery.

What the patient experiences

Vision loss that can be marked, with reduced contrast and color perception, and a perception that everything has a brown tinge
Improved near vision for a time in some patients, due to the myopic shift (“second sight”), which gradually lessens as the nucleus darkens
Glare, particularly in the dark
In extreme cases, only light perception

On examination, the red reflex is dull or absent, the fundus is hard to see, and the lens may be seen as a dark brown mass behind the pupil.

Pseudophakic comparison of the two eyes may reveal a marked difference.

Test your knowledge 10 questions from this article

Why surgery is more difficult

The nucleus is hard and needs more ultrasound energy to emulsify, which increases heat and turbulence and puts the corneal endothelium at risk (see corneal endothelial decompensation)
Hard nuclei are heavy, and fragments can damage the posterior capsule or fall into the vitreous
Zonular stress is greater, particularly in patients with pseudoexfoliation or trauma
Poor red reflex makes capsulorhexis harder, and trypan blue staining of the anterior capsule is often necessary
The risk of posterior capsule rupture and vitreous loss is higher (see vitreous loss in cataract surgery)
Wound burns and corneal edema are more frequent postoperatively

How surgeons plan for it

Preoperative specular microscopy to assess endothelial reserve
Use of dispersive and cohesive viscoelastic together (the soft shell technique) to protect the endothelium
Phaco chop or divide-and-conquer techniques that reduce the energy used
Careful hydrodissection and nuclear rotation
Staining the capsule
Considering manual small incision cataract surgery or extracapsular extraction when the nucleus is very dense and the endothelium is poor, particularly where phaco resources are limited

Postoperative course

Corneal edema is common in the first days and usually clears.

Dense nuclear fragments left behind or an IOP spike should be checked for.

Patients should be told about the possibility of prolonged edema, and about the longer recovery time compared with softer cataracts.

Brunescent Cataract (Cataracta Nigra): The Hard, Dark Nucleus and What It Means for Surgery

Talking to the patient before surgery

Patients with dense cataracts need honest information. Explain that the operation is more demanding, that the cornea may take longer to clear, that the risk of complications is higher than for a soft cataract, and that the final vision depends on the retina and optic nerve, which cannot be examined directly. Reassure them that, with good planning, most do very well, and that delaying further will only make the lens harder.

Assessing the back of the eye

Dense lenses hide the fundus, so a B-scan ultrasound is essential to exclude a detachment, a tumor, or a staphyloma. Check the pupil for a relative afferent defect, since an unexpected defect suggests optic nerve or retinal disease. Light projection and color perception are simple clinical tests that give some information about retinal function.

Early surgery as prevention

Public eye care programs have shown that earlier surgery reduces the number of brunescent lenses and their complications. In clinical practice, a patient who has had a gradual decline of vision and refuses surgery should be informed that the cataract will not shrink, and that waiting may make the operation less safe.

Prognosis

Visual results can be excellent when the retina and optic nerve are healthy, but the risk of complications is higher.

The best strategy is early surgery, before the nucleus becomes so hard.

References

Kelman CD. Phaco-emulsification and aspiration: a new technique of cataract removal. Am J Ophthalmol. 1967;64:23-35.
Ruit S, Tabin G, Chang D, et al. A prospective randomized clinical trial of phacoemulsification vs manual sutureless small-incision extracapsular cataract surgery in Nepal. Am J Ophthalmol. 2007;143:32-38.
Chylack LT Jr, Leske MC, McCarthy D, et al. Lens opacities classification system II (LOCS II). Arch Ophthalmol. 1989;107:991-997.
Gogate P, Optom JJ, Deshpande S, Naidoo K. Meta-analysis to compare the safety and efficacy of manual small incision cataract surgery and phacoemulsification. Middle East Afr J Ophthalmol. 2015;22:362-369.

Test yourself

A few questions straight from this article.

1 / 10 0 correct

What does the term cataracta nigra describe?
Cataracta nigra is the name given to the most extreme stage of a brunescent cataract, in which the deep brown nucleus has become almost black.
In what order does the lens nucleus change colour as a brunescent cataract develops?
The nucleus progresses from clear, to yellow, to amber, to brown, and finally to black as its proteins become cross-linked and pigmented.
Which processes leave the nuclear lens proteins cross-linked and pigmented?
Nuclear proteins aggregate and are modified by oxidation, glycation and ultraviolet exposure, which leaves them cross-linked and pigmented as the nucleus compacts.
What is the second sight reported by some patients developing a brunescent cataract?
A myopic shift can improve near vision for a time, but this second sight gradually lessens as the nucleus darkens further.
Why is the corneal endothelium especially at risk during surgery on a brunescent cataract?
A hard nucleus needs more ultrasound energy to emulsify, and the resulting heat and turbulence put the corneal endothelium at risk.
Which step helps achieve a capsulorhexis when the red reflex is poor in a dense cataract?
A dull or absent red reflex makes the capsulorhexis harder, so trypan blue staining of the anterior capsule is often necessary.
Which preoperative test assesses endothelial reserve before surgery on a hard nucleus?
Preoperative specular microscopy is used to assess the endothelial reserve, alongside planning such as the soft shell technique and low-energy nuclear disassembly.
When should manual small incision cataract surgery be considered for a brunescent cataract?
Manual small incision surgery or extracapsular extraction is considered when the nucleus is very dense and the endothelium is poor, particularly where phaco resources are limited.
Which investigation is essential when a dense brunescent lens hides the fundus?
Because a dense lens hides the fundus, B-scan ultrasound is essential to exclude a retinal detachment, a tumour or a staphyloma before surgery.
What is the best strategy for avoiding the higher surgical risk of a brunescent cataract?
Visual results can be excellent when the retina and optic nerve are healthy, but complication rates are higher, so the best strategy is surgery before the nucleus becomes so hard.

Ahmed Ophthalmologist

Writes and reviews the clinical articles on Educate. Every post is checked against peer-reviewed sources before it goes live.

Brunescent Cataract (Cataracta Nigra): The Hard, Dark Nucleus and What It Means for Surgery