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What did the pellucid marginal degeneration of the cornea?

The pellucid marginal degeneration (or pellucid marginal degeneration) is always bilateral corneal pathology (right eye and left eye are achieved fairly symmetrically). It is accompanied by an arch located in the lower part of the cornea which then protrude forward, over a lower peripheral corneal thinning area.

Cutting obtained through review Scheimpflug (topopraphe Tomey MSD 5) of an affected cornea of degererescence pellucida. The cut is made in the axis of the vertical flattening. Note the area where the steepness increases (in lower: red arrow), and the flattening, supportive of the central region of this Meridian (blue arrow).

The thinning is commonly observed in the lower quadrant of the cornea, and is fairly characteristic of this condition. In very advanced forms, this thinning is visible in less than the biomicroscope (slit lamp review). The cause of this condition is unknown. In some case, the notion of repeated eye rubbing is found.

Unlike Keratoconus, the corneal "protruding" tends to occur rather 'above', and not inside, the area of maximum thinning; the resulting deformation evokes a 'casesure' of the corneal curvature.  The degree ofastigmatism armature is variable but it can reach values above 20 D. The degree of myopia is usually lower than in case of Keratoconus (see also:) OPD and pellucid marginal degeneration)

The prevailing direction of the topographic cylinder (astigmatism induced by the toricite of the cornea) is reversed (branch known as "against the rule") because the vertical meridians are a flattening marked next to the box corresponding to the pupil of entry. The lowest corneal power therefore lies in a central vertical corridor, and the highest power zone stretches along the inferior cornea on both sides of the flattened vertical portion, with a curved direction characteristic (appearance in wings of mill).

Pellucid marginal degeneration may be related to Keratoconus in terms of the physio-pathogenesis, not by common biomechanical factors that govern the location of the ectasia. As with Keratoconus, there is Vascularity or lipid deposits within the corneal tissue.  The pellucid degeneration is a contraindication to the realization of a LASIK.

In this context, the use of the optical product is important to help differentiate between Keratoconus and pellucid degeneration, topographic aspects specular earlier ("aspect in Gallic mustache), although features, are not specific. Here is an example of map topographic and tomographic of horny affect EU of pellucid marginal degeneration (reverse astigmatism corrected at 6 D in the glass bezel).

Corneal topography and tomographic measurement (optical product) aquise thanks the tomograph Tomey TMS 5. The topographer enables previous specular analysis (Placido: lower left) and a series of cuts through a type Scheimpflug camera. We get a topography of elevation earlier (at the top left), posterior (upper-right). The subtraction of the anterior and posterior elevation provides a tomographic map (lower-right). Appearance in "Gallic whiskers" (map Placido) is very evocative, though nonspecific of pellucid marginal degeneration. The diagnosis is confirmed by the joint presence of a lower area of thinning. This thinning caused a change in the geometry of the anterior and posterior faces (protruding at the top of the spheres of reference, see maps of elevation). The vertical asymmetry is obvious (the local keratometries of the upper hemicornee are much lower than those of the lower hemicornee: This generates a significant aberrations of high rate: see: OPD and DPM)

Pellucid marginal degeneration is usually diagnosed later in life that of Keratoconus, usually between 40 and 60, when patients consult for a loss of Visual acuity due to a reverse astigmatism partially irregular, and a corneal topography is performed. It is possible that pellucid marginal degeneration begins earlier over the existence, but is revealed only to the 4th or 5th decade, to share the importance taken by reverse astigmatism. Non-surgical management of the D.M.P. (adaptation of rigid lenses) continues to occupy a prominent place in the management of this condition. Surgery often comes with a mediocre best corrected Visual acuity and a follow-up extended (at least 8 years old). The cornea transplant should be considered only for the case where the strain is extreme: his achievement is difficult due to the lower corneal thinning.

Corneal topographic map (acquisition Placido and scanning by slots - Orbscan) of pellucid marginal degeneration of the cornea. Note the typical appearance in axial curvature (lower-left) mode. The product map (bottom right) is also evocative; It reveals thinning extended predominant in lower.

Any topographic aspect wing' mill', or "crab claws" is not synonymous with pellucid marginal degeneration. Evidenced by this case of dystrophy of Cogan, where irregularities in the epithelial surface created a previous topographic pattern that evokes that of a DMP. There is however no less corneal thinning; on the contrary, there are certainly Hyperplasia with irregularity of the epithelial sheet.

false pellucid degeneration

Topographic appearance in specular map able to evoke a pellucid degeneration marginal, but related to an epithelial corneal irregularity located in lower answers (Cogan's dystrophy)

False pellucid marginal degeneration

Topographic appearance in specular map able to evoke a pellucid degeneration marginal, but related to an epithelial corneal irregularity located in lower answers (Cogan's dystrophy)

16 responses to "What is marginal pellucid degeneration of the cornea?"

  1. Guez Michael says:

    Thanks for this brilliant article.
    We note that in tangential the ' moustache ' disappears very often for the benefit of a ' round ' offset cone but in other case the moustache is also present in tangential.
    A pellucicide must meet these 3 criteria: moustache in axial and/or tangential and thinning?
    And if the axial mode does not let appear a crab claw appearance, is this the exclusion of the diagnosis of a DMP?
    Thank you

  2. Dr. Damien Gatinel says:

    This is actually possible in tangential, because this mode is more sensitive to the effects of the asphericity of the toricite. The diagnosis of pellucid degeneration must be faced with the presence of a less thinning (interest of myopia) because appearance in "moustache" is not specific and meets in case of Keratoconus whose apex is particularly moved lower.

  3. Michael Guez says:

    Thanks for your response

  4. Roux says:

    Hello
    I am 40 years old. I was diagnosed with a DPM on the left eye. My right eye is healthy. Is the pathology always bilateral or is it possible that the right eye is never reached?
    Should the recommended treatment be absolutely gradual (lentils, intra-corneal rings, cross linking). Indeed, having recently done test of soft lenses (other than for DPM) I could not stand the lenses, so is it useful to go through this step?

    Thank you for your answer.

  5. Dr. Damien Gatinel says:

    Classically, the DPM is bilateral; It is possible that on the one hand the changes to be minor, but in general, the symmetry of the breach between the two eyes is a characteristic sign of affection. 'Unilateral' Keratoconus is an alternative hypothesis, especially if you rub the left eye on a regular basis, or that you sleep on the left side in exerting pressure on your left eye. A corneal topography with measurement of the thickness of both corneas would certainly determinative.

  6. Donkeys says:

    Hello doctor,
    I'm 30 years old and I've been wearing glasses for 10 years.
    And there I saw a drop in my eyesight.
    Here I am at:
    OD:-2.75 (-1.5 to 180 degree)
    OG:-2.5 (-1.5 to 180 degree)
    I did a Topo disinfectant and I found:
    OD: 469 micro
    OG: 480 micro
    My doctor tells me that I have a keracotone start.
    What should I do?
    That it is the treatment you recommend me?
    Is my case may get worse?
    Thank you Doctor

  7. Dr. Damien Gatinel says:

    Your corneas are fine, and you have astigmatism, but only a topography of the cornea can confirm the diagnosis of Keratoconus. All thin corneas are not subject to wear or develop Keratoconus. The axis of your astigmatism and symmetry between the eyes suggests rather the presence of a congenital form of astigmatism. In all case I advise you to not or longer you rub your eyes, and a check topographic regular if the diagnosis of Keratoconus beginner was confirmed. In my experience, the judgment of the eye rubbing is enough to stop the evolution of Keratoconus (and I am in favour of the assumption that the friction is the princeps mechanism of Keratoconus, which is actually only a reaction of deformation permanent due to repeated trauma and disruption of the architecture of the cornea).

  8. Dr. Damien Gatinel says:

    The friction of the lenses represents a force whose magnitude is much lower than that, almost 'colossal' across the cornea, which is exerted on the corneal dome by knuckles, fingers, on the corneal dome. However, the lenses can induce a reshaping of the epithelium over time. But insist on the fact that the force that is exerted by these lenses on the top of the cornea is the simple pressure of the eyelids, and has nothing to compare with the fists, knuckles, etc.

  9. Brigitte says:

    Hello doctor,
    I have discovered with great attention your website/blog, trying to give me an opinion on medical decisions to take in the future regarding my vision.
    Indeed, aged 62 years, French resident abroad for many years, I am regularly followed by a hospital specialized in China.
    From the age of 20, I wore flexible lenses with great comfort to treat myopia (-5 per eye).... Until 2005, at my 50 years old, where suddenly they had become very uncomfortable (especially in the left eye). Meanwhile, astigmatism has been diagnosed. My doctor therefore prescribed rigid lenses, which I absolutely did not support. Since that day, I have been wearing glasses that correct me very correctly.
    Nevertheless, since 2005, I do regular exams: OCT, eye pressure, visual field...
    In 2009, a French hospital detected a possible DPM. I said that I never rubbed my eyes, nor did I sleep head in the pillow.
    More recently, it has been revealed a refinement of the optic nerve. And in June 2017, it was detected a risk of glaucoma. So I was prescribed Travatan drops every day. I actually have a history in the family. In addition, a cataract start is visible.
    Balance sheet today, my night vision is very handicapped by car headlights, preventing me from driving. By day, my vision remains correct, not annoying me too much in my work, involving 8-10 hours in front of a computer. Nevertheless, my eyes tire much faster than before and the vision is more blurred.
    In December 2017, a French hospital made me pass a topographical kératographie, as well as a pachymetry corneal.
    Today, an examination of the cornea appears to reconfirm the DMP. A first doctor offered me the break of rings, while another disadvises me, for the benefit of a Cross linking, before treating cataract.
    In view of my numerous pathologies, and contradictory opinions concerning the measures to be taken for the DMP, I seek your opinion, as a great specialist of this pathology.
    What would you advise me?
    Thank you in advance for paying attention to my case,
    Very sincerely,

  10. Dr. Damien Gatinel says:

    The marginal pellucida degeneration (DPM) is characterized by the onset of a particular astigmatism associated with a marked thinning of the cornea in the lower part, and a deformation of the corneal dome characteristic in topography. Corneal. If clinically the presentation of this condition has some peculiar characteristics, it could be a "border form of keratoconus". We observed case of DPM characteristics in patients who, without their knowledge, carried out repetitive gestures of lower friction (e.g. by wiping their eyes, by making cleansing with a gesture exerted on the "bottom" of the cornea). What is certain a priori is that cross linking has no interest in this affection. The ring pose may be tricky if the ring is to be put in the thinned area. The correction of astigmatism will be a bit random in all case, and the best would be to consider a correction in rigid or scleral lenses. By speakers, try to eliminate the possibility of a repeated local gesture that can explain the appearance of this characteristic corneal deformation. If you have a cataract (which has no connection to the DPM), an intervention is possible and the installation of an O-ring (to correct Cornéenn astigmatism) is an eventuality to consider.

  11. JG says:

    Hello doctor,
    I was diagnosed with a DPM at 35 years old. I was consulting for a sudden fall of vision, although I had felt a slight decline in recent years. That would confirm your hypothesis of occurring long before the diagnosis.

    I would like the DMP to be only a form of the KC because stopping friction could then stop its evolution. I have always been a great eye scrubber, sensitive to light, drought, work on screen... In recent months, I have probably aggravated the situation (fatigue, stress, crying...). By repeating my gesture of friction with phalanges on my chin, I realize the violence I inflicted on my corneas.

    5 min After the diagnosis, I was advised a CXL without addressing the question of friction. I hope your mechanical theory is the right one in the case of a DPM. I will wait a few months and consult at Rothschild.

    Do you know if people rub their eyes during sleep? The day I hold. But at night...

    Thank you.

  12. Dr. Damien Gatinel says:

    Thank you for your message and wise comments. I think today that the DMP is nothing more than a form of keratoconus that has the peculiarity of being very inferior to the level of the cornea (the keratoconus is characterized by a focal impairment; in the case of the DPM, the zone Thinned and weakened by friction is stately at a low distance from the periphery of the cornea. Know that the description of the marginal pellucida degeneration of the cornea was made at a time (years 50/60) in Europe, from a particular aspect of the cornea, which was thinned in inferior and distorted quite dramatically, then That it remained clear (hence the adjective "pellucida", meaning "clear"). The corneal topography did not exist, and the author of the article has gathered some observations to conclude that there is a new pathology... which when you think about it is nothing very different from a keratoconus for which deformation is particular, since lower thinning and "biomechanical rupture" are responsible for a paticulière deformation (marked central flattening, and peripheral camber in the lower). A legitimate question is: why is thinning so inferior? This could result from the conjunction of a friction technique or the maximum contact is exerted on the lower part of the cornea; This can happen without the patient's knowledge, because when rubbing his eyes, the eyelids close, and the eye rotates upward, which is variable according to the patients (Bell reflex). If you have a marked ascent of the globe when you rub your eyes, it is possible that the impact area of the friction is particularly shifted downwards from the cornea. But this area is physiologically thicker than the central region. It is therefore locally more resistant, and it is certainly necessary to rub harder and/or longer to train a biomechanical decompensation of the cornea with permanent deformation. This would explain the later onset of the DPM (in the late thirties or quarantine, typically). The CXL is useless, neither for the KC, nor for the DMP, other than to enrich a certain industry. Having said that, the realization of a CXL often causes a reduction in the stopping of friction; The patients operated instinctively have a reluctance to rub the eye, and the CXL which is a significant photochemical trauma induces a reduction of the corneal sensitivity (destruction of the nerve endings stromal). But it is certainly better not to rub spontaneously. In my humble opinion, one day will come when, when the understanding of what the KC will be at last, the CXL appears as a technique as inadequate in this context as was the bloodletting at the time of Molière for lung ailments. Your question about the possibility of night friction is very relevant; Patients who sleep on the belly and/or side, with restless sleep, often tend to rub their eyes on waking up, and may be in the night. Get yourself an eye protection shell from the pharmacist and carry there (or them) one night and you may be surprised as many patients realize that you sleep in support on the eyes, that the shells tend to "leave" at night due to FR Oats, etc. etc. The site Http://www.defeatkeratoconus.com Illustrates the importance of the sleep position in the genesis of the Keratoconus.

  13. ouzzine says:

    Hello doctor,

    I was diagnosed with two-eyed bilateral keratoconus with inféro-temporal bombing at the age of 25 (2016), as of today the Kératometriques indices remain relatively unchanged compared to the exams made a year ago but my doctor Noted a significant decrease in visual acuity, below the corrections:

    09/2017: OD ((70 ° – 1.75) + 0.75) OG ((110 ° – 1.50) PLANE)
    01/2019: OD ((70 ° – 3.00) – 0.25) OG ((110 ° – 2.25) PLANE)

    Currently I wear glasses. What clarification can you give me about this case ?
    How to block or retard this decrease in visual acuity knowing that my KC is not moving?

    Thank you for coming back.

  14. Dr. Damien Gatinel says:

    It is crucial to stop rubbing the eyes, and this is enough to stabilise the keratoconus (which is itself the consequence of a past of eye rubbing Important and vigorous). However, variations in asgtigmatisme may suggest a progression of keratoconus. The sleep position is also a parameter to be changed: if you sleep with a head position that exposes the eye to repeated contacts and pressures against the mattress, the pillow, it should be altered (sleeping on the back).

  15. Nabil says:

    Hello doctor,
    I have marginal pellucid degeneration and I wear semi-rigid lenses. I support them very well during the year but in the summer with the hot weather when I put them after a few hours my eyes start to turn red and this increases during the day which forces me to remove them and put back, is there a solution sach that in glasses the correction is not done very well.
    Thank you

  16. Dr. Damien Gatinel says:

    It may be necessary to provide for the instillation of lubricating eye drops to facilitate the wearing of rigid lenses in such situations.

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